World Meteorological Organization Instruments

WORLD METEOROLOGICAL ORGANIZATION

INSTRUMENTS AND OBSERVING METHODS

REPORT No. 50

WMO /TD-No. 541

1993 FOREWORD

Instrument developers are constantly striving to improve measurement systems to meet the desire of national meteorological services to achieve greater precision and accuracy and to satisfy performance requirements most efficiently and reliably. The introduction of the resulting new equipment or procedures means making changes, normally improvements, in meteorological observing systems.

These changes, however, can pose problems to the climatologist who would like a set of long-term homogeneous observations of high quality. The changes in instmments and observing practices can lead to changes in the quality or error characteristics of the data, which could be misintetpreted as a change in climate if not properly recognized.

To alleviate the danger of interpreting inhomogeneous upper-air data records, CIMO-X tasked a Rapporteur to u~dertake a study of "Historical Changes in Radiosonde Instruments and Practices." This report is the result of that effort.

The report summarizes historical infonnation from the 1930's to the early 1990's. However, instmments and observing practices will continue to change and, as we continue to be interested in detecting changes in our atmosphere, the effects of the changes in the measurement equipmeqt and procedures will need to be understood. Therefore, each National meteorological service is strongly encouraged to maintain complete and detailed records of changes made in upper-air and other meteorological observing systems and to endeavor to determine the effects of those changes on the data record.

I would like to thank Dr. Dian Gaffen, the Rapporteur who has prepared this report, and the National Oceanic and Atmospheric Administration (NOAA) of the USA for its support of this undertaking. I also thank those meteorological services who participated in this study and especially the national experts whose efforts in compiling their information will surely be appreciated by the readers of this report.

(Jaan Kruus) President of CIMO

FORWARD

These changes, however, can pose problems to the climatologist who would like a set of long-term homogeneous observations of high quality. The changes in instruments and observing practices can lead to changes in the quality or error characteristics of the data, which could be misinterpreted as a change in climate if not properly recognized.

To alleviate the danger of interpreting inhomogeneous upper-air data records, CIM:O-X tasked a Rapporteur to undertake a study of "Historical Changes in Radiosonde Instruments and Practices." This report is the result of that effort.

The report summarizes historical information from the 1930's to the early 1990's. However, instruments and observing practices will continue to change and, as we continue to be interested in detecting changes in our atmosphere, the effects of the changes in the measurement equipment and procedures will need to be understood. Therefore, each National meteorological service is strongly encouraged to maintain complete and detailed records of changes made in upper-air and other meteorological observing systems and to endeavor to determine the effects of those changes on the data record.

(Jaan Kruus) President of CIM:O

SUM:MARY

Because of the possibility that climate changes due to increases in atmospheric greenhouse gases and other pollutants or due to natural processes may influence human well-being, interest is growing in the analysis of historical meteorological data to detect climate variations and trends. Radiosonde data, which currently have the longest record available with global coverage, can be used to determine changes in upper-air temperature and humidity. However, interpreting archived radiosonde data properly requires know ledge of changes in instruments and observing practices that may influence the data record.

Because documentation of such changes was not readily available to the scientific community, WMO conducted a survey of Members on historical changes in radiosonde instruments and practices. Responses were received from 49 nations. The focus of the survey and of the responses was national changes affecting temperature and humidity measurements, although some information on station histories and wind and pressure measurements was also collected. On the basis of the survey results, this report presents chronological summaries of instrument changes and changes in observing and data reporting practices for each nation. For some nations, lists of relevant publications are given; bibliographies of general references on upper-air measurement systems are also included.

The survey included a question about techniques used to convert measured relative humidity and temperature to dewpoint depression. A comparison of 26 different techniques reported shows the heterogeneity in the global data due simply to this post-measurement treatment of the data. The different techniques can introduce a bias in the data that is generally smaller in magnitude than typical measurement errors and than differences in measurements among contemporary instruments. However, an important inhomogeneity results from the use of temperature, humidity, and pressure cutoffs in the methods, which affect the data from cold, dry regions most severely.

This survey was conducted to facilitate the interpretation of global radiosonde data archives by climate researchers. It is hoped that the information collected will allow easier identification of changes in upper-air temperature and humidity data that are related to changes in instruments or observing practices, and, possibly, adjustment of historical data to account for changes in biases in the record.

ill CONTENTS

Summary ...... ill

1. Introduction ...... 1

2. Survey Procedures ...... 2

3. Summary of Survey Results ...... 3

3 .1. Radiosonde Types ...... 4 3.2. Summary of Historical Changes by Nation ...... 12 General Format ...... 13 Afghanistan ...... ·...... 14 Argentina ...... 15 Australia ...... 16 Bahamas ...... 18 Belgium ...... 19 Belize ...... 21 Botswana ...... 22 Brazil ...... 23 Bulgaria ...... 24 Canada ...... 25 Cape Verde ...... 28 Chile ...... 29 China ...... 30 Costa Rica ...... 31 Cuba ...... 32 Czechoslovakia ...... 33 Denmark ...... 35 Finland ...... 37 France ...... 39 Germany ...... 40 Greece ...... 42 Guinea ...... 43 Hong Kong ...... 44 Iceland ...... 46 India ...... 47 Indonesia ...... 49 Ireland ...... 50 Israel ...... 51 Malaysia ...... 52 Netherlands ...... 53 New Zealand ...... 55 Pakistan ...... 58

iv Philippines ...... 59 Poland, Republic of ...... 60 Republic of Korea ...... 62 Romania ...... 63 Saudi Arabia ...... 64 Seychelles ...... 65 Singapore ...... 66 Solomon Islands ...... 68 South Africa ...... 69 Sudan ...... 70 Switzerland ...... 71 Thailand ...... 74 Tunisia ...... ~ ...... 75 Union of Soviet Socialist Republics ...... 76 United Kingdom of Great Britain and Northern Ireland ...... 80 United Republic of Tanzania ...... 84 United States of America ...... 85 VietNam, Socialist Republic of ...... · ...... 91

4. Dewpoint Algorithm Comparison ...... 92

5. Conclusions ...... 104

6. Bibliographies ...... 105

6.1. Bibliography on Dewpoint Depression Computations ...... 105 6.2. Bibliography on Radiosonde Performance and Comparisons ...... 106 6.3. Bibliography on the Use of Radiosonde Data for Climate Research ...... 109 6.4. Bibliography of Other Relevant References ...... 109

7. Acknowledgments ...... 111

8. Appendices

Appendix 1. Preliminary Questionnaire ...... 112 Appendix 2. Detailed Questionnaire on Historical Changes in Radiosonde Instruments and Practices ...... 113 Appendix 3. List of VIZ Manufacturing Company Radiosondes ...... 115 Appendix 4. Microfiche Copies of All Responses ...... Inside back cover

1. INTRODUCTION

Concern about the possibility of climate change due to natural geophysical processes and to anthropogenic pollutants is growing worldwide. Evaluation of variability and trends in climate requires atmospheric data from a variety of sources, but weather records maintained by national meteorological services are perhaps the best source of information about the recent climate. Interpretation of these records requires knowledge of past changes in instrumentation, observing methods, and reporting practices so that such changes cannot be misconstrued as climate changes nor can they obscure real atmospheric variations.

Atmospheric temperature has received the most attention, but water vapor figures prominently in several climate feedback mechanisms and is predicted to increase if temperatures rise because of increases in other greenhouse gases. Because of the longevity of the global radiosonde network, radiosonde observations are currently the most useful global data set for detecting long-term changes in tropospheric and stratospheric temperature and in tropospheric humidity. However, the network was not designed as a climate monitoring system and is inhomogeneous in both space and time. More important, the nature of these inhomogeneities has not been well documented.

To assist climate researchers in interpreting the data from the global radiosonde network, the Commission for Instruments and Methods of Observation decided at its tenth session in Brussels, 11-22 September 1989 (CIMO-X, Resolution 11), to "appoint a Rapporteur on Historical Changes in Radiosonde Instruments and Practices with the following terms of reference:

(a) To conduct an enquiry amongst Members on national historical changes in radiosonde temperature and humidity instruments, methods of observation and data reduction, and reporting practices;

(b) To collect bibliographic references on such changes;

This report presents those results. Section 2 outlines the survey procedures. Section 3 presents the main results of the survey and summarizes national changes in radiosonde instrumentation and practices. Section 4 presents an comparison of methods used to obtain dewpoint depression from measured upper-air temperature and relative humidity. Conclusions, bibliographies, and acknowledgments follow. The bibliographies include references of general interest on radiosondes and the use of radiosonde data for climate research; references specifically related to national radiosonde systems are given in the respective national summaries in Section 3. Appendices 1, 2, and 3 present, respectively, the preliminary questionnaire, the detailed questionnaire, and the list of VIZ Manufacturing Company radiosondes. Finally, Appendix 4 gives, in microfiche form, the original responses for the benefit of readers desiring more information than is presented in the national summaries. 2. SURVEY PROCEDURES

A two-part survey on historical changes in radiosonde instruments and practices was distributed to WMO Members by the Secretary-General. In June 1990, a preliminary questionnaire, included as Appendix 1, asked for the nomination of an expert to respond to a detailed second survey. That survey, included as Appendix 2 and distributed in October 1990, requested information on the following:

(1) the availability of reports documenting changes in upper-air observing systems or the effects of such changes;

(2) the availability of upper-air station histories;

(3) current and past radiosonde temperature and humidity instruments, including sensor type, accuracy and precision;

(4) changes in methods of observation, including time of observation and calibration techniques;

(5) changes in data reporting practices, including humidity cutoffs and special codes; and

(6) data conversions, including corrections made to the data and algorithms for computing dewpoint depression.

Experts were also invited to provide other relevant information and plans for further changes.

The focus of the survey was on national historical changes (because major changes tend to be made throughout a national observing network at about the same time) in radiosonde temperature and humidity instruments and practices (because these variables are of greatest interest· in detecting climate variations). Nevertheless, some station history information and some information on pressure and wind observations was received and is included in this report.

2 3. SUMMARY OF SURVEY RESULTS

In response to the preliminary survey, 66 WMO Members nominated experts and eight declined to participate. About half the WMO membership did not respond; however, not all Members operate upper-air stations. By 1993, 49 experts had responded to the second questionnaire. In a few cases, information was supplied through personal contact with the author or her colleagues. Responses were highly variable in terms of degree of detail, period of record covered, and the extent to which the effects of known changes could be explained.

In addition to the survey responses, information on historical changes was independently solicited from some radiosonde manufacturers. In some cases, there were discrepancies between manufacturer's information and national responses or between responses from different nations using the same radiosondes. Generally, follow-up questions clarified the ambiguity.

This section presents the main results of the survey on historical changes in radiosonde instruments and practices. First, a summary is presented, in tabular form, of radiosondes reported to have been used by responding nations during the past several decades. Next, a summary of current, past and planned changes in radiosonde instruments and practices is presented for each country, using the general format that is presented before the national summaries.

For the benefit of readers requiring station histories or other information that is not included in the national summaries, microfiche copies of each· complete response are included in Appendix 4. Notes in the national summaries direct readers to Appendix 4 when additional information is available. Detailed information on dewpoint depression algorithms (and manual methods for obtaining dewpoint depression) is deferred to Section 4.

3 3.1. Radiosonde Types

Table 1 summarizes information on all radiosondes that have been used by responding nations. Information on sensor type, error characteristics and meteorological range is included when available. When possible, the country of manufacture and an estimate of the approximate date of introduction, determined from the survey responses, is also given. Entries are left blank in the table if no information was available. Ambiguities or unresolved contradictions are indicated by a question mark. (In addition to the information in Table 1, an extensive list of radiosondes produced by VIZ Manufacturing Company (USA) is included in Appendix 3.)

In some cases, there were discrepancies in information provided by various nations, especially in instances where nations employ instruments manufactured in other countries. Representatives of radiosonde manufacturing firms and other radiosonde experts were consulted to resolve these. A major source of confusion is nomenclature. Radiosondes are, in various contexts, referred to by manufacturer's name, model number, or radio frequency of operation. In some cases, there is little distinction made between the radiosonde itself (the balloonbome instrument package), the tracking system, and the ground system used to compute meteorological variables and assemble the radiosonde report. An attempt has been made in this report to clearly distinguish the radiosonde from the ground systems and to be internally consistent in referring to different radiosonde types. However, some ambiguity remains on these points, especially for older systems.

4 Table 1. Summary of Radiosondes.

Manufacturer, Model, and Country of Temperature Sensor Humidity Sensor Type Pressure Sensor Date Frequency Manufacture Type and and Characteristics Type and Intro- Characteristics (Units: % relative Characteristics duced• (Units: •c) humidity) (Units: hPa)

A-22 Series

A-22-ill (403 MHz) USSR Spiral bimetal plate Goldbeater's skin Two bronze aneroid 1957 Range: -70 to +40 Range: 15-100 boxes with thermal rms error: 1.0 rms error: 5 compensation

A-22-IV (403 MHz) USSR Spiral bimetal plate Goldbeater's skin Two bronze aneroid 1960's Range: -70 to +40 Range: 15-100 boxes with thermal rms error: 1.0 rms error: 5 compensation

A-22-IV.D USSR Spiral bimetal plate Goldbeater's skin Two bronze aneroid 1962 Range: -70 to +40 Range: 15-100 boxes with thermal rms error: 1.0 rms error: 5 compensation

A-22-Vll (403 MHz) USSR Spiral bimetal plate Goldbeater' s skin Two steel aneroid Range: -70 to +40 Range: 15-100 boxes rms error: 1.0 rms error: 5 Compensation for thermal expansion not needed

Astor Radiosondes (Astor is a subsidiary of Philips)

Astor Raysonde Model Australia Thermistor rod sensor Lithium chloride sensor Single aneroid 1945 T.D.C. in duct in duct capsule

- Astor (72 MHz) Australia 1953

Astor (402 MHz) Australia Rod-type white Lithium chloride Single aneroid 1964 Astor Mk I (402 MHz) ceramic resistor capsule Astor Type 403 Errors up to 5°C due Pressure bias of 2-4 to ground-checking hPa greater than Bias of about 1 •c true value (too warm) in international comparisons

Atmospheric USA Thermistor with white Carbon hygristor Aneroid cell Instrumentation Research lead carbonate coating Range: 5-100 Range: 5-1050 (AIR) Intellisonde Range: -90 to +50 Accuracy: 3 Accuracy: 1 (403 and 1680 MHz) Accuracy: 0.5 Resolution: 0.01 Resolution: 0.01 Resolution: 0.01

Autovox Italy(?) 1960's

A W A (like the Astor Australia (?) Thermistor rod sensor Lithium chloride sensor Single aneroid 1953 RaysondeModel T.D.C.) in duct in duct capsule Temperature errors of up to 5°C at 50 hPa due to solar radiation

•survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

5 Table 1. Summary of Radiosondes (Continued).

Manufacturer, Model, and Country of Temperature Sensor Humidity Sensor Type Pressure Sensor Date Frequency Manufacture Type and and Characteristics Type and lntro- Characteristics (Units: % relative Characteristics duced• (Units: 0 C) humidity) (Units: hPa)

Bendix Radiosondes

Bendix/Friez Models USA Electrolytic tube Hair sensor in duct 1943 AN/AMQ-1 and 271-2 sensor in duct

Bendix WB (1680 MHz) USA Thermistor Carbon hygristor 1957

Bendix (403 MHz) USA Thermistor rod Carbon hygristor 1954

Chronometric Canada Bimetal Gold beater's skin 1945

Diamond Hinman (72.2 USA Thermistor Lithium chloride 1949 and 403 .1 MHz) MU19/AMT-4

Eclipse Radio Australia

Frieberg Germany(?) Bimeta1 Goldbeater' s skin 1968 Range: -70 to + 30 Range: 1-100 Accuracy: 0.2 Accuracy: 3

Graw Radiosondes

Graw H50 (27 MHz) Germany Bimetal cylinder OriginalJy human hair, Aneroid capsule 1950 Range: -70 to +30 later artificial hair Accuracy: 0.2 Range: 10-100 Accuracy: approx. 5

Graw M60 (27 and 403 Germany Bimetal cylinder Artificial hair Aneroid capsule 1960 MHz) Range: -80 to + 30 Range: 10-100 Accuracy: 0.25 Accuracy: approx. 5

Graw RSG (403 MHz) Germany Bead thermistor Originally psychrometric Aneroid capsule 1978 Range: -80 to +40 system, later carbon with capacitor Accuracy: 0.2 hygristor Range: 10-100 Accuracy: 8

Graw Minisonde TDFS-87 Germany Bead thermistor Carbon element Aneroid capsule 1987 (403 MHz) Range: -5 to +40 Range: 10-100 Range: 500-1060 Accuracy: 0.15 Accuracy: 5 Accuracy: 1 Resolution: 0.1 Resolution: 1 Resolution: 0.1

GZZ-2 (also called China Bimetal in a double Goldbeater' s skin Aneroid capsule Early GZZ59) (400 MHz) duct 1960's

•survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

6 Table 1. Summary of Radiosondes (Continued).

India Meteorological Department Radiosondes

India Meteorological India Bimetallic spiral pen Bimetallic spiral pen for Department Clock and Fan for dry bulb wet bulb Type Sondes

India Meteorological India Rod thermistor with Lithium chloride Aneroid capsule 1967 Department (401 and 1680 titanium dioxide hygristor MHz) Sondes coating (1992 version is called Mark m and Mk 3)

United Kingdom Radiosondes

Kew Pattern Mark (Mk, United Bimetallic strip Goldbeater' s skin Aneroid 1943 MK) I Kingdom

Kew Pattern Mark ll, United Cylindrical bimetallic Unvarnished goldbeater's Aneroid 1946 MKll, UK MKll Kingdom strip skin

Kew Mark llB, United Cylindrical bimetallic Unvarnished goldbeater's Aneroid· capsule 1952 UKMKllB Kingdom strip skin

Mark 3, MK3, U.K. RS3 United Coiled tungsten wire Goldbeater's skin Aneroid capsule 1977 Kingdom resistive element Poor exposure lead to Design fault in inaccurate readings (too temperature element dry) in clouds produced errors in 1979-1982 observations

Mark 4 - same as Viiisiilii Finland THERMOCAP- HUMICAP - capacitive BAROCAP- 1990 RS80 ceramic capacitive thin film element capacitive aneroid bead sensor Range: 0-100 sensor Range: -90 to + 60 Resolution: 1 Range: 3-1060 Resolution: 0.1 Accuracy: 2 Resolution: 0.1 Accuracy: 0.2 Accuracy: 0.5

Lang Germany Cylindrical bimetal Hair 1948

•survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

7 Table 1. Summary of Radiosondes (Continu~).

MARS and MRZ Radiosondes

MARS Series (1782 MHz) USSR MMT-1 Goldbeater's skin None 1983-84 (also known as MARZ) thermoresistor Range: 15-98 for Pressure is MARS-0 (Winds only) rod (covered with temperatures -40 to computed from MARS-1 (Temperature anti-radiation +SO•c radar height, and winds) hydrophobic varnish rms error: 10-15 temperature and MARS-2 (Temperature, since 1967) humidity humidity and winds) Range: -80 to +50 MARS-2-1 (Used with rms error: 0.5 Meteor and Meteorit tracking systems) MARS-2-2 (Used with Meteorit-2 tracking system)

MRZ (like MARS series USSR MMT-1 Goldbeater's skin None 1986 but designed for use with thermoresistor Pressure is AVK-1 computer-based computed from system) radar height, MRZ-2A (Winds only) temperature and MRZ-3A (Temperature, humidity. Humidity, and Winds)

Meisei Radiosondes (information is from Indonesia)

Meisei RSII76 Japan Rod thermistor (?) Carbon hygristor Ni-span aneroid 1976

Meisei RSll85 Japan VIZ rod thermistor Fast response carbon Ni-span aneroid with 1985 strip potentiometer

Mesural and Metox Radiosondes

Mesural MH-73A France Thermistor Goldbeater's skin 1965

Metox France Hair 1947

Metox France Bimetal Goldbeater' s skin 1964

Metox (403 MHz) Analog Thermistor rod VIZ carbon hygristor

Metra 972 (same as Czecho- Bimetal plate Unrolled hair 1962 Moltchanov RS-049 but slovakia Range: -70 to +40 made by Metra Praha)

Moltchanov RS-049 (also USSR Bimetal plate Hair Two aneroid boxes 1957 known as RZ-049; written Range: -70 to +40 Range: 20-100 as P3-049 in Cyrillic)

ONM France Spiral plate conductor 1930

"Survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

8 Table 1. Summary of Radiosondes (Continued).

Philips Radiosondes

Philips Mark II Australia Rod-type white Lithium chloride Single aneroid ceramic resistor capsule Errors up to 5•c due Pressure errors of 2- to ground-checking 4 greater than true value Height errors approximately 25 m

Philips Mark II 1/2 Australia VIZ carbon hygristor in 1982 housing allowing radiation error

Philips Mark m Australia VIZ carbon hygristor in 1983 redesigned housing that reduced errors to < 5

Philips RS4, Models I, II Australia Lithium chloride before and m 1984 VIZ carbon hygristor (#1186-161) after 1984

RKZ (or RKS) Series Radiosondes

RKZ (1782 MHz) USSR Thermistor Goldbeater's skin Range: -80 to +50 Range: 15-100

RKZ-1 USSR Low inertia bead Goldbeater's skin Calibrated RKZ-1A thermoresistor Range: 1-100 baroswitch Range: -80 to +SO Accuracy: 2 Accuracy: 1.0

RKZ-2 (used with Meteor USSR MMT-1 rod type Goldbeater's skin None or Meteorit-1) thermistor Range: 5-100 Pressure is Range: -80 to +50 Accuracy: 7 computed Accuracy: 0.7

RKZ-5 (used with USSR Bimetal Goldbeater's skin None 1972 Meteorit-2) Range: -80 to +50 Range: 5-100 Pressure is Accuracy: 0.5 Accuracy: 5 computed [rms error: 0.88] [rms error: 6.2]

RM-12 Poland Goldbeater's skin

"Survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

9 Table 1. Summary of Radiosondes (Continued).

RZ-042 USSR Normal hair 1954

RZ-049, RS-049, R-049 USSR Bimetal plate Rolled hair Two aneroid boxes 1957 (see Moltchanov RS-049) Range: -70 to +40 Range: 20-100

Space Data Division, USA Ceramic flake Carbon hygristor, same Barometric 1988 Model 909-10-01 thermistor coated with as in VIZ "B" sonde integrated water repellent temperature- silicone and white controlled solid state lead carbonate paint sensor (aneroid capsule)

Swiss Radiosondes

Swiss Sondes Model I, la, Switzerland Bimetallic strip Hair (1942-1959) Single pair of 1942 n,m Goldbeater' s skin (1959- aneroid capsules, 1990) manufactured by Graw (1942-1971) Double pair of aneroid capsules (1971-1990)

SRS-400 (Meteolabor) Switzerland Thermoelement VIZ Accu-Lok Hygristor Water hypsometer 1991 13286-065

Viiisiilii Radiosondes

Viiisiilii RS11 (25 MHz) Finland Bimetal strip Normal hair/rolled hair Aneroid capsule 1938

Viiisiilii RS12 (25 MHz) Finland Bimetal strip Rolled hair Aneroid capsule 1959

Viiisiilii RS13, RS15 (25 Finland Bimetal strip Rolled hair Aneroid capsule 1965 MHz)

Viiisiilii RS18 (25 MHz) Finland Bimetal ring Rolled hair Aneroid capsule 1976

Viiisiilii RS21 Series, Finland Bimetal ring in a duct Rolled hair Double aneroid 1978 including RS21-12C (400 . After 1978, HUMICAP capsule and 1680 MHz) capacitive thin film element

Viiisiilii RS80 Series, Finland THERMOCAP- HUMICAP - capacitive BAROCAP- 1981 including RS80-15 (403 ceramic capacitive thin film element capacitive aneroid MHz); bead sensor Range: 0-100 sensor RS80-16 (1680 MHz) Range: -90 to +60 Resolution: 1 Range: 3-1060 (basic sonde used with Resolution: 0.1 Accuracy: 2 Resolution: 0.1 independent windfinding Accuracy: 0.2 Accuracy: 0.5 system); RS80-15N, RS80-15P (Omega Navaid windfinding); RS80-15L (Loran-C Navaid windfinding)

. •survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

10 Table 1. Summary of Radiosondes (Continued).

VIZ Radiosondes (the following includes most of the VIZ radiosondes mentioned in the survey responses; a much more comprehensive inventory is given in Appendix 3)

VIZ AMT -4 Series (1680 USA Rod-type thermistor Lithium chloride until Mechanical 1954 MHz) with white lead 1957 baroswitch carbonate coating Thereafter, carbon hygristor

VIZ Model 1395 Series USA Rod-type thermistor Carbon hygristor Baroswitch 1975 (403 MHz) with white lead Accuracy: <4 carbonate coating Range: 5-100 Accuracy: <0.4 Range: -90 to +50

VIZ "A", Model1492-510 USA Accu-Lok (factory- Accu-Lok carbon Baroswitch 1986 baselined) carbon hygristor thermistor rod, with white lead carbonate · coating Infrared radiation error at night can exceed I.S•c above 10 hPa

VIZ "B", Model 1492-520 USA Accu-Lok (factory- Carbon hygristor, as in Baroswitch 1988 baselined) carbon VIZ "A" sonde, in a thermistor rod, with "J"-shaped duct lined white lead carbonate with black laminate coating Hygristor may be less Infrared radiation influenced by solar and error at night can sonde heating than VIZ exceed 1.s•c above "A" Model1492-510 10hPa

VIZ Mk I Series (403 USA Accu-Lok (factory- Accu-Lok carbon Baroswitch 1980 MHz) baselined) rod hygristor thermistor

VIZ Mk 11 Series USA Accu-Lok rod Accu-Lok carbon Continuously 1991 (403/1680 MHz) thermistor hygristor variable capacitive Range: -90 to +60 Range: 5-100 aneroid sensor Accuracy: 0.2 Accuracy: 2 Range: 3-1080 Resolution: 0.1 Resolution: 1 Accuracy: 0.5 Resolution: 0.1

W eathermeasure USA

Whitely Electric Mark 11 1947

"Survey responses indicate the equipment was in use by the date listed. Actual date of introduction may be earlier.

11 3.2. Summary of Historical Changes by Nation

This section summarizes current, past and planned changes in radiosonde instruments and practices for each country, using the general format that precedes the national summaries. The guiding principle in developing these summaries was to include all major changes in an easily understood and consistent format. In general, radiosondes are referred to by type only. For information on radiosonde sensors, the reader should consult Table 1. In some cases, radiosonde sensor changes were made without changes in the name of the radiosonde type, and these are noted in the national summaries.

Where ambiguities or discrepancies in national summaries were not reconciled, question marks in the text indicate that the information may not be accurate. The list of national summaries reflects geopolitical entities in existence at the time of the responses (1990-1992). Updates of the WMO Catalogue of Radiosondes and Upper-Air Wind Systems in Use by Members may be useful for extending these chronologies to the present.

12 GENERAL FORMAT:

NAME OF COUNTRY

I. CURRENT INSTRUMENTS AND PRACTICES

Radiosonde type and ground equipment used at the time of the questionnaire response are given. For details about sensors, refer to Table 1. Observing practices, such as observation times, methods of converting observed data to reported data, temperature or humidity cutoffs, and corrections applied to the data, are summarized.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Significant changes in temperature and humidity instruments and practices, and the dates of implementation, are noted.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Changes in instruments and practices that are being implemented or planned are summarized.

N. STATION HISTORIES

The availability and form of station histories is noted. If station history information provided by the expert is not overly complex, a summary is presented. Otherwise, the reader is referred to the original response in the microfiche Appendix 4 for details.

V. PUBLICATIONS

A list of published reports regarding upper-air temperature and humidity observations is provided when available. This list includes material particular to the nation in question. More general references are listed in the bibliographies (Section 6).

VI. NATIONAL EXPERT

The name, address, and telephone number of the expert who provided the above information is included.

VII. MISCElLANEOUS INFORMATION

This section includes relevant information that does not fall in any of the above categories, and is included only when required. For example, if information from a different country is helpful in interpreting the record from the country in question, the former country is noted.

13 AFGHANISTAN

I. CURRENT INSTRUMENTS AND PRACTICES (As of 25 November 1990)

RKZ-5 radiosondes.

I/. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1958: RZ-049 radiosondes. 1962: Introduced A-22-IV.D radiosondes. 1972: Introduced RKZ-5 radiosondes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

N. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

N.A. Noory and M.H. Adeel; Aerological Station; Meteorological Authority; Ansari Watt; P.O. Box 165; Kabul, Afghanistan; TEL: 25541/45-26541145

14 ARGENTINA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 10 May 1991)

Six (of eight) stations use VIZ Mk II radiosondes. The rest use Vaisala RS80 and RS80-15N radiosondes. Tracking systems differ from station to station and include Navaid, Decca Model WF1 radar, Vaisala RT18 and Vaisala ME12 radiotheodolites, and optical theodolite.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1956-1964: Two stations (87750 and 87934) used Graw radiosondes. 1957: Introduced Vaisala RSll radiosondes. 1964: Introduced Vaisala RS13 radiosondes. 1971: Introduced Vaisala RS15 radiosondes. 1972: Introduced Vaisala RS18 radiosondes. 1976: Introduced Vaisala RS21 radiosondes. 1981: Introduced automatic reception. (?) 1984 and 1990: Introduced Vaisala RS80 and RS80-15N radiosondes. 1990: One station used VIZ Mk II radiosondes. 1990: Introduced microcomputer systems. 1991: Introduced VIZ Mk II radiosondes at five stations. The six VIZ stations are: 87024, 87155, 87344, 87418, 87567, 87623.

Different tracking systems have been used at each station. The list given under "/. CURRENT INSTRUMENTS AND PRACTICES" includes all historical systems.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Microcomputer systems will continue to be introduced.

IV. STATION HISTORIES

See microfiche Appendix 4 for station-by-station historical information.

1963: Began operations at station 87155 (Resistencia Airport) to replace station 87157. 1974: Began operations at station 87418 (Mendoza Airport) to replace station 87420. Both moves involved location changes of less than 10 km.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Carlos Alberto Damboriana; Jefe Division Estaciones Meteorol6gicas, Fuerza Aerea Argentina; Servicio Meteorol6gico Nacional; 25 de Mayo 658; (1002) Capital Federal; Buenos Aires; Argentina

15 AUSTRALIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 18 December 1990)

Vaisala RS80 radiosondes. Humidity measured to -60°C or 20 hPa, whichever occurs first. Observations generally at 2300 UTC at all stations, sometimes at 1100 UTC at some stations.

I!. PAST CHANGES IN INSTRUMENTS AND PRACTICES

The following summarizes changes made throughout the network. See microfiche Appendix 4 for station-specific information.

Radiosondes: 1943: Bendix/Friez radiosondes with electrolytic tube temperature sensor and hair hygrometer. 1945: Introduced Astor Raysonde Model T.D.C. 1947-48: Introduced AWA radiosondes in small numbers. 1953 (approximately): Introduced Astor (72 MHz) radiosondes. 1964: Introduced Astor (402 MHz) radiosondes. 1976: Began progressive introduction of Astor (MK I, 402 MHz) radiosondes. 1978-79: Introduced Philips Mark IT radiosondes. 1982: Introduced Philips Mark IT 112. 1983: Introduced Philips Mark m. 1985: Introduced offsets into factory calibration system, reducing pressure errors to 1-2 hPa. 1987: Introduced Vaisala RS80-15 in May at capital cities and at remainder of stations progressively throughout the year.

Ground Systems: 1980: Introduced electronic calculators to replace completely manual system. 1987: Introduced Vaisala PPll processor with the RS80-15 radiosondes to replace a combined receiver/frequency counter, which in turn had earlier replaced a separate Astor receiver and frequency counter. 1987: Introduced Vaisala DigiCORA at Casey, Antarctica (89611). 1989: Introduced DigiCORA at Macquarie Island (94998) and Davis, Antarctica (89571). 1990: Introduced DigiCORA at Cocos Island (96996) on 28 November.

Data Reporting: Before 1982: With the lithium chloride strip, significant humidity levels were based on a maximum 2 oc dewpoint tolerance between significant levels. Humidity was not measured below -40°C. 1982: With introduction of VIZ carbon hygristor, humidity was measured to -60°C or 100 hPa, thereafter coded as //. For constant low humidity (below approximately 30%), all dewpoint depressions reported as 30 (coded as 80). Humidity data were selected with a scale rule with variable allowable humidity tolerance. 1987: With introduction of Vaisala PPll processor, began current humidity reporting practices.

16 Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

1991: Planned introduction of Vaisiilii DigiCORA to Mawson, Antarctica (89564). Planned conversion to VaisaHi PC-CORA system with RS80 radiosondes.

Iv. STATION HISTORIES

See microfiche Appendix 4 for detailed station histories.

V. PUBLICATIONS

Hancock, D.E., 1953: The effect of solar radiation on radiosonde temperature measurements. Australian Meteor. Mag.

Radio Corporation Pty. Ltd.: Astor 403 Radiosonde. Melbourne. (Sales pamphlet)

Radio Corporation Pty. Ltd., 1945: Radiosonde Transmitter Audio Modulated Type. Melbourne.

U. S. Department of Commerce, Weather Bureau, 1943: Instructions for modulated audio frequency radiosonde observations, Circular P, Fourth Edition, U.S. Government Printing Office, Washington, DC, 98 pp.

VI. NATIONAL EXPERT

B. Bradshaw; Supervising Meteorologist; Bureau of Meteorology; 150 Lonsdale Street; Melbourne Victoria, Australia; TEL: (03)669-4000

VII. MISCElLANEOUS INFORMATION

Information on accuracy of radiosonde pressure measurements, 1950 to 1988, is included in the microfiche Appendix 4.

17 BAHAMAS

I. CURRENT INSTRUMENTS AND PRACTICES (As of 25 Apri11991)

VIZ modell392-520 (?)radiosondes. The algorithm for converting relative humidity and temperature to dewpoint depression is the same as is used in the United States.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1979: Station established 14 December. Observations at 1200 UTC. 1980-81: New carbon hygristor introduced. Relative humidity transfer equation changed for the new sensor. 1980-87: Manual calculations of sounding data. 1988: Began taking 0000 UTC observations during hurricane season when a cyclone threatens the Bahamas. 1988: Introduced VIZ "B" (model1492-520) radiosondes and new computer system.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV, STATION HISTORIES

Available from U.S. National Climatic Data Center.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Neville G. Woodside; Meteorological Department; Clarence A. Bain Building; Thompson Boulevard; P.O. Box N8330; Nassau, Bahamas; TEL: 809 32-54048/9

18 BELGIDM

I. CURRENT INSTRUMENTS AND PRACTICES (As of 27 December, 1990)

Vaisa.Ia RS80 radiosondes with tracking by Navaid method using the Omega network. Dewpoint depression not transmitted for temperatures below -40°C.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Radiosondes: 1956-30 Apri11961: Kew Mk IT. 1 May 1961-31 May 1961: Kew Mk IT at 0000 UTC; Graw H50 at 1200 UTC. 1 June 1961-11 Feb. 1964: Graw H50. 12 Feb. 1964-28 Feb. 1965: Graw H50 at 0000 UTC; Graw M60 at 1200 UTC. 1 March 1965-31 Dec. 1979: Graw M60. 1 Jan. 1980-31 June 1980: Graw M60 at 0000 UTC; VIZ at 1200 UTC. 1 July 1980-31 Dec. 1989: VIZ. 1 Jan. 1990- : Vaisa.Ia RS80.

Tracldng Methods: 1956-31 Aug. 1958: Metox radiotheodolite. 1 Sept. 1958-3 July 1963: Decca WF1 radar. 4 July 1963-31 Dec. 1979: Selenia Meteor 200 RMT 1L radar. 1-Jan. 1980-31 Dec. 1989: EEC windfmder. 1 Jan. 1990- : Navaid method, Omega network.

Observation Times: 1956-31 March 1957: 0200 and 1400 UTC. 1 Apri11957- : 0000 and 1200 UTC.

Dewpoint Depression Algorithms: See Section 4.

Ill. PLANNED CHANGES IN INSTRUMENI'S AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

Institut Royal Meteorologique (IRM) Statistiques quinquennales: Observations Aerologiques Station d'Uccle 1956-1960, Bruxelles.

IRM Statistiques quinquennales: Observations Aerologiques Station d'Uccle 1961-1965, Bruxelles.

IRM Statistiques quinquenrtales: Observations Aerologiques Station d'Uccle 1966-1970, Bruxelles.

19 IRM Statistiques quinquennales: Observations Aerologiques Station d'Uccle 1971-1975, Bruxelles.

IRM Statistiques quinquennales: Observations Aerologiques Station d'Uccle 1976-1980, Bruxelles.

IRM Statistiques quinquennales: Observations Aerologiques Station d'Uccle 1981-1985, Bruxelles.

IRM, 1964: Investigation of the reliability of radiosonde measurements in Uccle with the method of twin sondes, Publications IRM no. 43, Brussels.

VI. NATIONAL EXPERT

D. De Muer; Institut Royal Meteorologique de Belgique; Avenue Circulaire 3, B-1180 Bruxelles; Belgique; TEL: (02) 374.43.00

20 BELIZE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 8 November 1990)

VIZ (1680 :MHz) radiosondes, tracked by radiotheodolite and precalibrated at the factory. Observation times have always been 2315 and 1115 UTC, but during tropical storm emergencies an observation is made every 6 hours. A semi-automatic minicomputer based system has always been in operation except for 1981. For relative humidity below 20%, dewpoint depression is reported as 80 in the coded message and 30 in the archived data. Otherwise, dewpoint depression algorithm is the same as is used in the United States.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1981: Minicomputer failed, so manual computations were made.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Implementing a fully-automated computer system starting 1 November 1990.

Iv. STATION HISTORIES

Station history available from the U.S. National Climatic Data Center.

V. PUBLICATIONS

The Belize station is part of a cooperative network with U.S. National Weather Service (NWS). For further information contact the Overseas Operation Division of the NWS or the U.S. National Climatic Data Center.

W. NATIONAL EXPERT

Carlos Fuller; Permanent Representative of Belize with WMO; P.O. Box 717; Belize City; Belize; TEL: 025-201112012/2054

21 BOTSWANA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 24 April 1991)

Vaisalii. RS80-15 radiosondes, pre-calibrated at the factory, and Vaisa.Ia ME12 radiotheodolite. Observations at 1200 UTC. Wind calculations made with a programmed calculator. Other upper-air data are calculated manually. Dewpoints are calculated using a Vaisala slide rule.

1/. PAST CHANGES IN INSTRUMENTS AND PRACTICES

January 1985: Began operation at one station, Gabarone Sir Seretse Khama Airport (68240).

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Planned establishment of three new radiosonde stations in 1991 using Vaisala radiosondes and DigiCORA equipment.

N. STATION HISTORIES

No station changes have been made.

V. PUBLICATIONS

W. NATIONAL EXPERT

S.K. Mazhani; Botswana Meteorological Services; P.O. Box 10100; Gaborone; Botswana

22 BRAZll..

I. CURRENT INSTRUMENTS AND PRACTICES (As of 2 March 1992)

Three agencies operate upper-air stations: (1) Ministerio da Agricultura, Departamento Nacional de Meteorologic (DNMET), mainly in northeast Brazil. (2) Ministerio da Aeromiutica, Departamento de Electronica e Protegao de Voo (DEPV), at major airports. (3) Ministerio da Marinha, Diretoria de Hidrografla e Navega~ao (DHN), mainly at island sites.

DNMET and DHN stations use mainly Vaisala RS21-12C radiosondes. DEPV stations use either Vaisala RS80-15N or VIZ Mk n radiosondes. Observations are made between 1100 and 1200 UTC, although five DEPV stations take 0000 UTC observations.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Both VIZ and Vii.isala radiosondes have been used. See microfiche Appendix 4 for station-by station information.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Iv. STATION HISTORIES

See microfiche Appendix 4.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Yomar Morada Souza; Rua Babilonia, 13 APT. 501; TIJUCA-CEP 20511; Rio de Janiero; Brazil

VII. MISCElLANEOUS INFORMATION

This information was obtained through personal contact, not through WMO channels.

23 BULGARIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 7 May 1991)

MARS radiosondes and Meteorit radar at Sofia (15614) and Kardjali (15730). Observation times are 0000, 0600, and 1200 UTC at Sofia and 0000 and 1200 UTC at Kardjali. See Section 4 for dewpoint depression algorithm.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1957-63: RZ-049 radiosondes and Malahit radiotheodolite. 1964-67: A-22-IV radiosondes and Malahit radiotheodolite. 1968-86: RKZ (1782 MHz) radiosondes and Meteorit radar. 1987- : MARS radiosondes and Meteorit radar.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Station histories are available from the Institute of Meteorology and Hydrology.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Nevna P. Kovacheva; Bulgarian Academy of Sciences; Institute of Meteorology and Hydrology; Bulgaria, Sofia 1184, Blvd. "Lenin" 66; TEL: 72 22 71/75

24 CANADA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 6 December 1990)

VIZ radiosondes (produced in Canada by Valcom) tracked by GMD radiotheodolite at most stations. At these stations, humidity data are not reported for temperatures below -65°C and relative humidities less than 9%. No temperature corrections are applied. Vaisala RS80 and DigiCORA ground systems at some stations. At these stations, no humidity cutoffs are used, and temperature corrections are applied.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1945-55: Two groups of stations: (1) Canadian Meteorological Service stations using Canadian designed Chronometric radiosondes. Windfmding, if any, was accomplished optically. (2) Joint Arctic Weather Stations (JAWS), operated jointly with United States. Radiosondes supplied by the U.S. Weather Bureau were used with Metox or SCR-685 radiotheodolite. 1955-56: Introduced 403 1v.1Hz radiosondes and Metox and SCR-658 radiotheodolites to replace Chronometric radiosondes. In any year, radiosondes were from the same manufacturer (VIZ Manufacturing Company) as those used by U.S. Weather Bureau. 1960: Began gradual (2 year) introduction of exposed, white-coated rod thermistor with no radiation correction applied. Data conversion identical to U.S. Weather Bureau. 1962: Began installation of GMD radiotheodolites at 20 (of 34) sites. 1963: Introduced VIZ (107 :MHz) radiosondes at Ocean station "P" to replace Chronometric radiosonde. 1964-66: Completed conversion of all stations to GMD radiotheodolites. 1966-68: Introduced carbon element to replace lithium chloride humidity sensors. 1973: Introduced new humidity duct to improve readings at high solar elevation angle. 1974: Converted Ocean station "P" from 107 MHz to 403 MHz, which resulted in improved data. 1977: Introduced monolobe (solid state) antenna to replace mechanical Conscan Spinner in GMD radiotheodolites. No evidence of change in wind accuracy. 1978: Introduced ADRES minicomputer system. Wind data were calculated automatically, but an operator extracted the raw meteorological data. 1978: Changed humidity algorithm to allow computations for all temperatures above -65°C. Previously, humidity data were terminated at -40°C. 1980: Converted 18 of 33 stations to use transpondersondes. These were flown when the elevation angle in flight was expected to be less than 12 o; produced a considerable improvement in wind data. 1980: Introduced a new carbon hygristor. The supplied algorithms resulted in relative humidity readings 2 to 5 % too low in the range 90 to 100% . 1980-82: Radiosondes were supplied by VIZ. 1983: Introduced a new humidity algorithm with ADRES to correct the values in the 90 to 100% range. 1985: Converted Prince George (71896) to Vaisili RS80 radiosondes and DigiCORA. Winds were computed using Omega, but a software problem produced erroneous winds. . A temperature correction is applied to the data (as compared with the GMD/ADRES stations, which do not apply a temperature correction).

25 1986: Introduced pre-baselined radiosondes. Previously all sondes had undergone a manual baseline lock for temperatures and humidity. Discovered that the manual baseline technique was prone to producing an incorrect humidity lock at low relative humidity, which resulted in data below 60% being biased too high. It is estimated that at 20% relative humidity the relative humidity error could be as great as 10% . 1987: Closed station at Shelbourne, Nova Scotia. Opened one at Yarmouth (71603) using VIZ Mk I radiosondes and Beukers W8000 Navaid system; windfmding was accomplished using Loran-C. 1988: Converted station at Coral Harbour (71915) from GMD radiotheodolite to Vaisala DigiCORA. Same comments as for Prince George apply here. (See 1985 entry.) 1989: Converted station at Fort Nelson (71915) from GMD to Vaisala DigiCORA. Solved the Omega wind problem for all three DigiCORA stations. The RS80 radiosondes were no longer baselined for temperature and humidity; the values were accepted as accurate. Pressure was still baselined and corrected.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Yarmouth will be converted to the VIZ Zeemet system with the VIZ Mk IT radionsonde in early 1991. Winds will be calculated using cross-chain Loran-C. Saskatoon (Saskatchewan) will become operational in mid-1991 using the VIZ Zeemet system. Starting in 1992, a gradual conversion of all stations to Navaid technology is planned.

IV. STATION HISTORIES

Station histories are available in (1) Station Inspection Report and (2) Station Information System (a computerized system) from the Atmospheric Environment Service, Attention: CCAA. In addition, station histories including station names, locations, and periods of record are available in the Climatological Station Catalogue (1989, six volumes). See microfiche Appendix 4 for additional information.

V. PUBLICATIONS

Atmospheric Environment Service (ABS), 1987. Format Documentation for the Digital Archive of Upper Air Data Identification by Element.

ABS, 1989. Documentation for the use of software to generate reports for the Digital Archive of Upper Air Data, UA User's Manual.

Department of Transport, Meteorological Branch, 1957: Maps of Upper Air Winds over Canada, Toronto.

Harley, W.S., 1980: Northern Hemisphere Monthly Mean 50 kPa and 100 kPa Height Charts, CU-1-80, ABS, Downsview.

Titus, R.L., 1965: Upper Air Climate of Canada - Average. Extreme. and Standard Deviation Values 1951-1960, ABS, Toronto.

26 Titus, R.L., 1967: Upper Air Climate of Canada - Charts of Monthly Geopotential. Temperature and Humidity 1951-1960, AES, Toronto.

Titus, R.L., 1973: 1961-1970 Mean. Extreme and standard Deviation Values of Canadian Upper Air Stations. CU-8-73, Downsview.

Monthly journals (currently out of print) were published from 1959 to August 1976 by AES.

VI. NATIONAL EXPERT

G. Klein; Atmospheric Environment Service; 4905 Dufferin St.; Downsview, Ontario; M3H 5T4; Canada; TEL: (416) 739-4589.

VII. MISCElLANEOUS INFORMATION

Additional information, including algorithms and station-specific information, is included in microfiche Appendix 4.

27 CAPE VERDE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 26 December 1990)

VIZ radiosondes tracked by radiotheodolite. Humidity not reported for temperatures less than -40°C. One observation daily at 1200 UTC.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1949-1970: Canadian radiosondes tracked by optical theodolite. Radiosondes had bimetallic temperature sensor, goldbeater's skin humidity sensor, and aneroid pressure sensor. 1970: Introduced VIZ radiosondes and radiotheodolite. Mid-1970's: During the GATE period, an American military mobile upper-air station was in operation at Praia (08589) using VIZ radiosondes. 1979: Moved l'lle du Sal station (08594) about 3 km.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Station history information through 5 July 1975 should be available from the Institute of Meterology and Geophysics of Portugal. Thereafter the data have been recorded in notebooks.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Osvaldo Silva; Director, Meteo Cape Verde; Ministerio dos Transportes, Comercio e Turismo; Servi9o Meteorol6gico Nacional; C.P. 76; Sal; Cape Verde

28 CHILE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 11 July 1991)

Vaisa.Ia RS80-15N radiosondes w,ith MicroCORA ground system.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Dates of changes listed below are approximate. Specific dates for each station are given in the microfiche Appendix 4.

Instruments: 1957-60: Bendix (1680 MHz) radiosondes. 1960-68: AMT-4 Signal C radiosondes; 1968-71: Bendix WB radiosondes. 1971-85: VIZ radiosondes, various models. 1981: Introduced VIZ Accu-Lok hygristors. 1985-88: Introduced Vaisa.Ia RS80-15N radiosondes with MicroCORA ground system, gradually.

Practices: Until introduction of Vaisa.Ia equipment, humidity cutoffs were employed as in the United States.

Observation Times: 1957-65: 0000, 1200 and 1800 UTC. 1966-71: 0000 and 1200 UTC. 1972-88: 0000 and 1200 UTC (?). 1988-1991: 1200 UTC only at four stations, 0000 and 1200 UTC at Quintero (85543).

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Station locations have not changed since observations began in 1957. See microfiche Appendix 4 for additional information.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Carlos Parra Arena; Direccion Meteorologica de Chile; Departamento Instalaciones Meteorologicas; Casilla 717 Santiago; Chile; TEL: 6019001

29 CHINA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 20 November 1990)

GZZ-2 (code-sending) radiosonde, precalibrated at the factory and checked at stations for pressure and humidity. Tracked by Model 701 secondary radar. Observations twice daily at 1115 UTC and 2315 UTC. Data reduction is semiautomatic with a pocket computer. Solar radiation corrections are applied to the daytime temperature data with a fixed correction table. When the ascent rate of the balloon 1 1 is less than 150 m min- or more than 600 m min- , the data are rejected. When the temperature is below -60°C, relative humidity is not reported. Data are reported only up to 10 hPa. See Section 4 for dewpoint depression algorithm.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1949-1952: Two stations used Diamond radiosondes. 1952-1959: Nineteen stations employed Viiisala RS-12 radiosondes. 1957: Introduced virtual temperature correction. 1959: Introduced solar radiation correction to daytime temperature data. 1955-1969 (?): Gradual implementation of RZ-049 radiosondes at all stations. 1964- : Gradual implementation of GZZ-2 radiosondes at all stations.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Some information included in reports listed below. See microfiche Appendix 4.

V. PUBLICATIONS

Academy of Meteorological Sciences, 1988: 30 Years of the Academy of Meteorological Sciences (1956-1986).

State Meteorological Administration, 1988: Regulations on the Upper-air Observation, Vol. 4, Meteorological Publishing House, 212 pp. ·

State Meteorological Administration, 1976: Manual on the Upper-air Observation.

VI. NATIONAL EXPERT

Huang Bingxun; State Meteorological Administration; Baishiqiaolu No. 46; Western Suburb; Beijing; China; TEL. 890371

30 COSTA RICA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 1 May 1991)

VIZ (1680 :MHz) radiosondes tracked by radiotheodolite One observation daily at 1200 UTC (0600 local time). For relative humidities below 20%, the dewpoint depressions are reported as 80 in the coded message and 30 in the archived data. When the temperature is below -40°C, relative humidity is reported as missing(// in coded message, and 999 in archive). No corrections are applied to the temperature or relative humidity data.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1981: New carbon hygristor was introduced, and the relative humidity transfer equation was changed.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Installation of a new recording system is planned. rv. STATION HISTORIES

No station location changes have occurred. Station history is available from the U.S. National Climatic Data Center.

V. PUBLICATIONS

Grandoso, H., A. Vargas, and V. Castro, 1981: Characteristics of the Free Atmomhere Over Costa Rica and Its Relations With Precipitation. Ministry of Public Works, National Geographic Institute, San Jose, Costa Rica.

W. NATIONAL EXPERT

Guillenno Vega G.; Instituto Meteorologico Nacional; Apartado Postal 7-3350-1000; San Jose, Costa Rica

WI. MISCELLANEOUS INFORMATION

Received time-share computer system for calculating wind data.

31 CUBA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 10 May 1991)

MARS-2-2 radiosondes and Meteorit-2 radar. See Section 4 for dewpoint algorithm.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: 1940's-1961: Used U.S. radiosondes. 1962-65: ? 1966: Introduced RKZ-1A, RKZ-2 radiosondes with Meteorit tracking system. 1981: Introduced RKZ-5 and MARS-2-2 radiosondes with Meteorit-2 tracking system. 1989: Introduced semiautomatic microcomputer system.

Practices: 1957: Began making observations at 0000 and 1200 UTC. Earlier practice was to make observations at 0300 and 1500 UTC. 1989: Began reporting humidity at a111eve1s. Earlier practice was to report humidity as missing for temperatures below -40°C. 1966-1989: Computed dewpoint depression using Vaisala slide rule. 1989: Introduced new dewpoint depression algorithm.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

Luciano Armaro Argiiez; Jefe Departamento Aerologia; Instituto de Meteorologia; Academia De Ciencias de Cuba; Casablanca; Cuba

32 CZECHOSLOVAKIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 10 December 1990)

MARS radiosondes (manufactured by Metra Praha), precalibrated at the factory. Dewpoint depression algorithm is given in Section 4.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Information given for Prague and Poprad. This summary combines the two histories, because they are only slightly different. For further details, see the microfiche Appendix 4.

Radiosondes and Tracking Methods: 1949: Began regular measurements at Prague with Lang and Vaisala radiosondes. 1951: Began regular measurements at Propad. 1954: Introduced RZ-042 radiosondes. 1957: Introduced RZ-049 radiosondes. Introduced radiotheodolite. 1961-63: Introduced Metra 972 radiosondes (copy ofRZ-049 made by Metra Praha) and A-22-ill radiosondes. 1967-68: Temperature and humidity measurements interrupted at Prague. 1968-69: Introduced A-22-IV radiosondes alternated with MARS radiosondes. 1970: Introduced MARS radiosondes in April. Introduced radar tracking. 1986: Introduced new steel aneroid capsule pressure sensor to MARS radiosondes, which resulted in- more accurate temperature measurements (?).

Observation Times: 1957: Observation time changed from 0300 and 1500 UTC to 0000 and 1200 UTC. 1959-86: Number of observations varied from two (at 0000 and 1200 UTC) to four (at 0000, 0600, 1200 and 1800 UTC) daily during different periods at each station.

Data Reporting: 1956: Introduced corrections for the inertia of the temperature sensor. 1957: Introduced radiation corrections. 1979: Introduced new dewpoint depression algorithm. Previously, the dewpoint depression was determined graphically, based on Figure 1 in Handbuch der Aerologie (see Publications) 1980: Introduced practice of replacing relative humidity under 10% with the value 10%. 1980: Introduced semiautomatic minicomputer system at Prague. 1990: Introduced practice of ending relative humidity data at 300 hPa.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Implementation of a complete Vaisala system is planned.

33 Iv. STATION HISTORIES

Station moves are noted for Prague, in June 1967, and Propad, in December 1977. See microfiche Appendix 4 for further details.

V. PUBLICATIONS

Hesse, W., 1961: Handbuch der Aerologie. Akademische Verlagsgesellschaft, Geest and Portig K.G., Leipzig.

VI. NATIONAL EXPERT

Anna Benesova; Cesky hydrometeorologicky ustav; 143 06 Na Sabatce 17, Praha 4; Komorany 143 06; CSFR

34 DENMARK

I. CURRENT INSTRUMENTS AND PRACTICES (As of 11 December 1990)

Vai.sala RS80 radiosondes and CORA or DigiCORA ground systems. Observation times are 1100 and 2300 UTC.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: Nov. 1947-0ct. 1948: VIZ radiosondes (?)used at Agmagssalik (04360). Nov. 1958-Aug. 1962: VIZ radiosondes used at Narssarssuaq (04270). Otherwise, Danish stations have used Vai.sala radiosondes, as follows: Before 1978: RS11, RS12, RS13, RS15, and RS18 tracked with manually or semimanually operated receivers. 1 Dec. 1978: Introduced RS21 at Agmagssalik (04360). 18 Nov. 1979: Introduced RS21 at Kap Tobin (04340). 23 Dec. 1979: Introduced RS21 at Jregersborg (06181). 25 Sept. 1980: Introduced RS21 at Scoresbysund (04339). 13 Oct. 1982: Introduced RS80 at T6rshavn (06011). 27 Dec. 1982: Introduced RS80 at Jregersborg (06181). 9 Oct. 1983: Introduced RS80 at Denmarkshavn (04320). 20 Nov. 1983: Introduced RS80 at Angmagssalik (04360). 2 Feb. 1985: Introduced RS80 at Egedesminde (04220). 19 March 1985: Introduced RS80 at Narssarssuaq (04270). 1 Oct. 1985: Introduced RS80 at Scoresbysund (04339). The RS21 and RS80 are tracked automatically with either CORA or DigiCORA receivers.

Observation Times: 1 June 1945-31 Dec. 1947: 0600 and 1800 UTC. 1 Jan. 1948-31 Dec. 1954: 0230 and 1430 UTC. 1 Jan. 1955-31 March 1957: 1030 and 1330 UTC. 1 Apri11957-6 June 1961: 1030 and 2230 UTC. 1 July 1961- : 1100 and 2300 UTC.

Calibration Techniques: The RS21 and RS80 radiosondes are precalibrated at the factory, and only minor corrections are applied immediately before release. The RS11, RS12, RS13, RS15, and RS18 were also pre calibrated for pressure and temperature, but humidity sensors were calibrated at stations, normally 1 week before use. The hair hygrometer calibration was performed at 97% relative humidity and ambient humidity.

A nomogram was used for computing dewpoint depression from 1967 until the introduction of automatic systems. A copy is in the microfiche Appendix 4.

35 Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

See microfiche Appendix 4 for a complete listing of station locations and moves.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Klaus Hedegaard; Danish Meteorological Institute; Lyngbyvej 100; DK-2100 Copenhagen 0, Denmark; TEL. 45 31 29 21 00

36 FINLAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 23 May 1991)

Vaisala RS80-15N radiosondes.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Radiosondes: Vaisala radiosondes, as follows: 1938-1955: RSll, bimetal strip thermometer, normal hair hygrometer. 1956-1959: RSll, bimetal strip thermometer, rolled hair hygrometer. 1960-1966: RS12, bimetal strip thermometer, rolled hair hygrometer. 1963-64: Introduced automatic radiosonde receivers. 1967-1975: RS13 and 15, bimetal strip thermometer, rolled hair hygrometer. 1976-1981: RS18, bimetal ring thermometer, rolled hair hygrometer. 1981: RS21-12 CN, bimetal ring thermometer, capacitive thin ftlm HUMICAP hygrometer. 1982- : RS80-15N, capacitive bead THERMOCAP thermometer, HUMICAP hygrometer.

Observation Times: 1957: Changed observation time from 0200 and 1400 to 0000 and 1200 UTC. 1987: Began making three soundings daily at 0000, 0600, and 1200 UTC.

Data Reporting/Conversions: 1981: Introduced MicroCORA system, which allows temperature and humidity reports at all levels and includes solar radiation correction. Previously humidity was measured only up to 300 hPa. 1986: Solar radiation correction program changed at stations 02836, 02935, and 02963.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

MicroCORA ground systems will be changed to DigiCORA in 1992-1993.

IV. STATION HISTORIES

Station histories can be found in some of the publications listed.

V. PUBLICATIONS

Huovila, S., and A. Tuominen, 1986: Comparisons between automated and radiosonde and upper wind observations in Finland. Meteorological Publications No. 3, Finnish Meteorological Institute, Helsinki, 35 pp.

Huovila, S., and A. Tuominen, 1990: On the influence of radiosonde lag errors on upper-air climatological data in Finland 1951-1988. Meteorological Publications No.14, Finnish Meteorological Institute, Helsinki, 29 pp.

37 The Finish Meteorological Institute, 1984: Statistics of radiosonde observations 1961-1980. Meteorological Yearbook of Finland, Vol. 61-80, Part 3, Helsinki.

Rossi, V., 1973: On the development of experimental aerology in Finland. VaisaHi. News, 58, Ref. No. B 227.

Rossi, V., 1959: Summary of the radiosonde observations at Ilmala in the years 1938-1955. Meteorological Yearbook of Finland. Aerological Summaries: Aerological Observations in Finland, Helsinki.

W. NATIONAL EXPERT

Osmo Kemppi; Finnish Meteorological Institute; Box 503, Vuorikatu 24, 00101 Helsinki, Finland. Information on sales of Vaisa.Ia radiosonde equipment to other countries was provided by Henrik Hultin, Vaisa.Ia Oy, Helsinki, Finland.

WI. MISCELLANEOUS INFORMATION

A complete list of algorithms is included in the microfiche Appendix 4. Vaisa.Ia radiosonde equipment has been purchased by various organizations in countries that did not provide responses to the questionnaire. It is not certain whether Vaisa.Ia equipment is used operationally in these countries. They include: Algeria, Angola, Bangladesh, Burma, Cameroun, Chad, Colombia, Ecuador, Estonia, Ethiopia, Hungary, Iran, Iraq, Italy, Japan, Kenya, Kuwait, Mali, Mexico, Mozambique, Niger, Nigeria, Norway, Papua New Guinea, Portugal, Senegal, Spain, Sweden, Taiwan, United Arab Emirates, Venezuela, Yemen, Yugoslavia, and Zambia.

38 FRANCE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 17 December 1990)

Vaisa.Ia radiosondes.

I!. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1929: Radiosonde invented by Pierre Idrac and Robert Bureau. 1930: Constructed a small set of radiosondes (bathermoradio). Introduced disk to replace cylindrical apparatus. 1932-33: Constructed first series of model ONM 200 radiosondes for the International Polar Year. 1934: Introduced hygrometer to radiosondes. 1937-38: For a 6-month period, made daily soundings from St. Cyr and over the North Atlantic. After 1939: Introduced spiral plate conductor. Prior to 1947: Introduced clock movement in radiosondes. 1947: Introduced ftrst Metox radiosonde. 1965-66: Introduced C.d.C. (?)and Mesural radiosondes to replace Metox. 1986- : Began introduction of Vaisa.Ia radiosondes, first for shipboard observations in the North Atlantic. 1987-89: Introduced Vaisa.Ia radiosondes at Kerguelen, Nouvelle-Amsterdam, and Terre-Adelie. 1989-91: Introduced Vaisa.Ia radiosondes at the remaining stations in the French network.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

Numerous publications are listed in the microfiche Appendix 4.

VI. NATIONAL EXPERT

M. Beaurepaire; Service des Equipements et des Techniques Instrumentales; Direction de la Meteorologie Nationale; 7 rue Teisserenc de Bort; BP 202; 78195 Trappes Cectex; France; TEL. 30 51 27 90

VII. MISCElLANEOUS INFORMATION

Detailed descriptions of early French radiosondes are included in the microfiche Appendix 4.

39 GERMANY

I. CURRENT INSTRUMENTS AND PRACTICES (As of 20 February 1991)

MARS radiosondes tracked by Meteorit radar at most stations in the former German Democratic Republic. Vai.sala RS80 radiosondes tracked by radar at the rest of the stations. Different dewpoint depression algorithms are used at the two sets of stations. See Section 4 for details. Monthly means are coded as Climat-Temp in FM 75-:-Code. For stations 035, 338, 410, 739, and 868, the mean is for 0000 and 1200 UTC; for stations 184, 393, 486, and 548, it is for 0000 UTC; and for station 384, it is for 1200 UTC.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Complete listings for all stations are included in the microfiche Appendix 4. In general, the following (very approximate) progression is applicable at stations of the former German Democratic Republic:

1970: Introduced RKZ radiosondes (various models) tracked by radiotheodolite to replace Frieberg radiosondes tracked by optical theodolite. 1986: Introduced MARS radiosondes (various models) tracked by radiotheodolite.

At the rest of the stations, the following (very approximate) progression is applicable:

About 1963: Introduced Graw M60 radiosondes to replace Graw H50 radiosondes, both tracked by radar. 1988: Introduced Graw RSG radiosondes at some stations, tracked by radar. 1990: Introduced Vai.sala RS80 radiosondes tracked by radar.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

In 1991, Vai.sala RS80-30 radiosondes(?) will be introduced at Dresden (486), Lindenberg (393), Greifswald (184), and Meiningen (548), successively.

IV. STATION HISTORIES

Detailed descriptions (monthly reports etc.) are available for all stations. For more information contact the German Weather Service (DWD), Library Division, 6050 Offenbach/Main. Info1111ation on individual station histories is included in the microfiche Appendix 4.

V. PUBLICATIONS

Beelitz, P., 1954: Radiosonden. Berlin.

40 Friedberger Werkstiitten fiir Elektromeche~, Radiosonde Modell Freiberg, Beschreibung durch den Hersteller. Vorschriften and Betriebsunterlagen Nr. 9, BHB Aerologie, Deutscher Wetterdienst Offenbach.

Hering, W.U.A., 1970: Vorbereitende Untersuchungen im Hinblick auf die Einfiihrung des Radiosonden Systems METEORIT/RKS. Intemer Bericht.

Radiosonde RKS-2. Beschreibung durch den Hersteller, Moskau.

Steinhagen, H.: Die Neue Aerologische Miniatur-Radiosonde MARZ. Intemer Bericht, Lindenberg.

Trenkle, F., 1982: Die Entwicklung der Deutschen Radiosonde von 1930-1955, Intemer Bericht, DFVLR.

Vaisala, 1989: DigiCORA and Marwin User's Guide. Helsinki, Finland.

VI. NATIONAL EXPERT

M. Kurz; Head of Synoptic Division; Deutscher Wetterdienst; Frankfurter StraBe 135; 6050 Offenbach am Main; Germany; TEL: 069-8062-0, Telex: 4152817

41 GREECE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 30 July 1991)

Vaisala RS80 radiosondes and MicroCORA ground systems.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1952: 1680 MHz (VIZ?) radiosondes and GMD radar tracking systems from the United States. 1978: Introduced Vaisala RS21-12CN radiosondes and CORA with Omega windfmding. 1978: Introduced Vaisala Dewpoint Slide Rule Type ABDS 11. Previously, a slide rule "Temperature Radiosonde Temperature Evaluator, U.S. Weather Bureau No. 230B, WS Form 1188B" was used and relative humidity not reported below 10%. 1988: Introduced Vaisala RS80-15N radiosondes and MicroCORA with Omega windfmding.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Introduction in 1991 of MicroCORA at Mikra (Thessaloniki) to replace the GMD system.

Iv. STATION HISTORIES

Since 1952, three stations have been in operation: Helliniko (International Airport Athens), Heraklio Airport (Crete), Mikra Airport (Thessaloniki).

V. PUBLICATIONS

VI. NATIONAL EXPERT

George Melanitis; Ministry of National Defense; General Air Staff; Helenic National Meteorological Service; P.O. Box 73 502; 166 03 Hellinikon; Athens, Greece; TEL. 9629415- 9615810

42 GUINEA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 11 June 1991)

None

1/. PAST CHANGES IN INSTRUMENTS AND PRACTICES

At Conakry: 1947-67: Metox radiosondes tracked by radiotheodolite. Observations at 1200 UTC. 1975-81: Vaisala radiosondes, model not noted, but sensors were bimetal thermometer and hair hygrometer.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Re-installation of radiosonde station at Conakry is planned.

Iv. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

Mamadou Lamine Bah; Direction Nationale de la Meteorologie; BP 566; Conakry; Republique de Guinee.

43 HONG KONG

I. CURRENT INSTRUMENTS AND PRACTICES (As of 28 November 1990)

Vaisala RS80 radiosondes. Temperature and relative humidity values reported at all levels. Dewpoint depression is calculated using tables from Vaisala.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Radiosondes: 1949-1968: Kew Mk liB (U.K. Meteorological Office). 1969-1974: Vaisala RS13. 1975-1980: Vaisala RS18. 1981-1983: Vaisala RS21. 1984- : Vaisala RS80

Observation Methods: 1949-1957: Observations made once every morning at 0000 UTC. 1957-1980: Observations made twice daily at 0000 and 1200 UTC. 1981: Introduced fully-automatic minicomputer-based system. Observations made twice daily at 0000 and 1200 UTC.

Data Reporting: 1949-1980: Reported all temperature and relative humidity values without corrections. 1981-1989: Radiation correction applied to temperature data as follows: 0000 UTC ascents: -0.1 oc at 200 hPa, -0.5°C at 100 hPa 1200 UTC ascents: +0.7°C at 200 hPa, +0.8°C at 100 hPa 1990: Introduced new radiation correction for temperature data for 0000 UTC ascents only as follows: -0.2°C at 200 hPa, -0.3°C at 100 hPa

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

For additional information see the Technical Information Sheet on "Upper Air Meteorological Measurements in Hong Kong" in microfiche Appendix 4.

V. PUBLICATIONS

Apps, R.F., 1971: Comparison between the results obtained with the new MK liB and the Vaisala RS13 radiosondes under operational conditions in Hong Kong. Royal Observatory Technical Note No. 31, Hong Kong.

44 Leong, H. C., 1976: Hong Kong upper-air climatological summaries 1961-1970. Royal Observatory Climatological Note No. 1, Hong Kong.

Wong, N.Y., 1988: Comparison between the results obtained with the Vai.sala RS18 and the Chinese GZZ59 radiosondes under operational conditions in Guangzhou. Royal Observatory Technical Note (Local) No. 42, Hong Kong.

VI. NATIONAL EXPERT

C.M. Tarn; Royal Observatory Hong Kong; Nathan Rd; Kowloon; Hong Kong; TEL. 732 9200

45 ICELAND (VEBURSTOFA isLANDS)

I. CURRENT INSTRUMENTS AND PRACTICES (As of 11 April 1990)

Vaisa.Ia RS80 radiosondes tracked using Marwin.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Radiosondes and Ground Equipment: 1946-1954: Unknown radiosondes and SRC 658 ground equipment. 1954-1990: VIZ radiosondes (last type VIZ 1492 series) and AN/GMD. 1990- : Vaisa.Ia RS80 radiosondes and Marwin.

Practices: Same data reporting practices as employed by the United States. 1957: Changed observation times from 0300, 0900, 1500, and 2100 UTC to 0000, 0600, 1200, and 1800 UTC. 1970: Began making only 0000 and 1200 UTC observations.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

Borgb6r H. J6nsson; V~urstofa islands; Bustabavegur 9; 150 Reykjavik; Iceland

46 INDIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 10 February 1992)

Two radiosonde types, both manufactured by the India Meteorological Department, are used. A 1680 MHz sonde (tracked by autotracking radiotheodolite) is used at 7 stations; a 401 MHz sonde (tracked by radar or remote-control manual tracking radiotheodolite) is used at 28 stations. Observations are at 0000 and 1200 UTC. For temperatures less than -40°C or relative humidity less than 15%, no humidity data are reported. For dewpoint depression algorithm, see Section 4.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Before mid-1960's: India Metorological Department clock-type radiosondes north of 20°N lat.; fan type radiosondes south of 20 °N lat. Until 1967: Corrections were applied to temperature data when solar elevation angle exceeded 2.5°. 1988: Introduced redesigned relative humidity ducts to reduce solar radiation effects. 1988: Introduced computerized calibration system to replace servo-controlled analogue system. 1990: Introduced semiautomatic computer to replace manual computations using Temperature/Humidity/Dew Point Evaluators.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

TV. STATION HISTORIES

Detailed station histories are included in the microfiche Appendix 4.

V. PUBLICATIONS

India Meteorological Department, Upper Air Observation Manuals. Instruments Division, Meteorological Office, New Delhi, Chapters 1 to 7.

Raghavan, S., B.P. Ghosh, and P.R. Rao, Adoption of 1680 MHz radiosonde ground equipment (WBRT-R) to Indian radiosonde network: Its installation and circuit alignment techniques. Scientific Report No. 134, Office of Deputy Director General of Meteorology (Upper-air Instruments).

Srivastav, S.K., S.K. Bindra, and P.K. Paliwal, 1989: A solid state (1680 MHz) radiosonde transmitter. Fourth WMO Technical Conference on Instruments and Methods of Observation, TECIMO-IV, 4-8 September 1989, Brussels, Instruments and Observing Methods Report No. 35, World Meteorological Organization, Geneva.

Srivastav, S.K., S.K. Bindra, M.K. Gupta, and M.P. Bhardwaj, 1992: Solid state switch for radiosonde sensors. Mausam, 43, 1, 87-90.

47 Srivastav, S.K., M.C. Asthana, M.P. Bhardwaj, and S.K. Bindra, 1990: Remote controlled antenna system for radiosonde data. Mausam, 41, 1, 142-144.

VI. NATIONAL EXPERT

S .K. Srivastav, Deputy Director General of Meteorology, India Meteorological Department, Lodi Road, New Delhi 110003; India; TEL: 611451

48 INDONESIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 24 December 1991)

Mainly VIZ 1392 series radiosondes with various types of ground equipment. Observations daily at 0000 and 1200 UTC. Calculations made manually except at Cengkareng (96749). Dewpoint is determined with a dewpoint slide rule. Geopotential heights are calculated with a VaisaHi Aerogram, Type RSAP 15 (Me 82B).

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Meisei RSIT76 and RSIT85 and VIZ 1392 series radiosondes have been used. See microfiche Appendix 4 for station-specific changes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

See microfiche Appendix 4.

V. PUBLICATIONS

VI. NATIONAL EXPERT

H.L.H. Siregar; Department of Communications; Meteorological and Geophysical Agency; J.L. Arief Rakhman Hakim No. 3; P.O. Box 3540; Jakarta (10340); Indonesia; TEL: 375508

49 IRELAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 12 November 1990)

Vaisa.Ia RS80-15N radiosondes with DigiCORA ground system

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: 1943: Introduced Kew Pattern MK I radiosondes. 1947: Introduced Kew Pattern MK IT radiosondes. 1965: Introduced B.M.O. Cintel (Automatic Radiosonde Recording). 1977: Introduced Vaisa.Ia RS21-12C radiosondes and AR16 recorder system. 1983: Introduced Vaisa.Ia RS80-15 radiosondes. 1986: Introduced Vaisa.Ia RS80-15P radiosondes with Omega Navaid windfmding system. 1988: Introduced Vaisa.Ia RS80-15N radiosondes with Omega Navaid windfmding system. 1990: Introduced Vaisa.Ia DigiCORA automatic ground system.

Observation Times: 1943: 0000 and 1200 UTC. 1948: Changed to 0300 and 1500 UTC. 1957: Changed to 0000 and 1200 UTC.

Data: 1943-77: For temperatures below -40°C, humidity values from the Kew MK I and MK TI radiosondes were discarded. Humidity values less than 5% were taken as 5%, and above 100% as 100%. 1956-77: Solar radiation and lag corrections based on the "Scrase" formulae were applied to temperature data. (See U.K. summary for reference.) 1977- : Corrections determined by Vaisa.Ia were used.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

PCSERV and METGRAPH2 will be added to the DigiCORA system to permit editing of data input.

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

E.J. Murphy; Officer-in-Charge; Meteorological Service; Valentia Observatory; Cahirciveen; Co. Kerry; Ireland; TEL: 0667-2176

50 ISRAEL

I. CURRENT INSTRUMENTS AND PRACTICES (As of 7 February 1993)

VIZ Mk II digital microsonde used as part of the fully-automatic microcomputer-based rawinsonde system, CV 700, made by Atir Ltd. (Israel).

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: 1955: Metox radiosondes. 1968: Introduced VIZ 1392 radiosondes and GMD tracking system. 1991: Introduced VIZ 1492 radiosondes and CV 700 computerized rawinsonde system. 1992: Introduced VIZ Mk II digital microsondes.

Observation Times and Locations: 1955: One observation daily at 1200 UTC at Be'er Yaakov. 1962: Two observations daily at 0000 and 1200 UTC at Bet Dagan. 1976: Three or four observations daily at 0000, 0600, 1200, and 1800 UTC at Bet Dagan.

Data Conversions: 1955: Manual computations. 1976: Began making computations with a mainframe computer. 1991: Introduced fully-automatic system.

The publication listed below includes data conversion algorithms.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

TV. STATION HISTORIES

Partial stations histories for 1955-77 are included in the publication listed below.

V. PUBLICATIONS

Rosenthal, H., 1977: Automatic system for analysis of radiosonde and radiotheodolite data. Series C. No. 33. (in Hebrew)

VI. NATIONAL EXPERT

A. Manes; Deputy Director; Israel Meteorological Service; P.O. Box 25; Bet Dagan 50250; Isreal; TEL: 972-3-9682187.

VII. MISCELLANEOUS INFORMATION

The original response from Israel is not included in the microfiche Appendix 4.

51 MALAYSIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 29 October 1990)

Vaisalii RS80-15N radiosondes. Observations daily at 0000 and 1200 UTC, except at Tawau (96481) where only 0000 UTC observations are made. The last humidity level is reported when the dewpoint is -65°C or when 200 hPa level is reached, whichever comes frrst.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1965: Started observations at Bayan Lepas (48601) with Vaisala RS18 radiosondes. 1968: Started observations at Kota Kinabalu (96471) with Vaisala RS18 radiosondes. 1971: Started observations at Kuantan (48657) with Philips RS4 radiosondes. 1972: Started observations at Petaling Jaya (48648) with Philips RS4 radiosondes and at Kota Bharu (48615) with Vaisala RS21-12C radiosondes. 1976: Started observations at Kuching (96413) with Philips RS4 radiosondes. 1978: Started observations at Tawau (96481) with Vaisala RS21-12C radiosondes. 1981: Started observations at Bintulu (96441) with Philips RS4 radiosondes. 1983: Changed to RS80-15 Vaisala RS80-15 radiosondes at Kota Bharu (48615). 1984: Note: Philips RS4 radiosondes carried lithium chloride hygristors unti11984; after 1984 they carried carbon hygristors. 1987: Changed to Vaisala RS80-15 radiosondes at Bayan Lepas (48601), Kota Kinabalu (96471), and Tawau (96481). 1988: Changed to Vaisalii RS80-15 radiosondes at Petaling Jaya (48648), Kuantan (48657), Bintulu (96441), and Kuching (96413).

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Vaisala RS80-15N radiosondes and DigiCORA ground systems will be installed at Petaling Jaya and Kuantan in December 1990. All manual equipment in the other upper-air stations will be converted in stages to fully-automatic equipment during 1992-1996.

IV. STATION HISTORIES

Histories for upper-air stations could be compiled and supplied if required.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Chim Ah Hong; Malaysian Meteorological Service; Jalan Sultan; 4667 Petaling Jaya; Malaysia; TEL. P .J. 7569422

52 NETHERLANDS

I. CURRENT INSTRUMENTS AND PRACTICES (As of 21 December 1990)

VaisaJ.a RS80-15N radiosondes and DigiCORA ground system.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1947: Whitely Electric Mark IT radiosondes with homemade ground equipment. Observations at 0300 and 1500 UTC. 1 Jan. 1957: Introduced radar tracking. 1 Jan. 1957: Introduced radiation correction, including time lag correction. 1 April1957: Changed observation times to 0000 and 1200 UTC. January 1968: Introduced albedo correction to radiation correction. 1 Sept. 1972: Began generating coded message using KNMI mainframe computer. 1 Jan. 1973: Introduced VIZ model1205 and VIZ model1221 radiosondes with homemade ground equipment. 15 May 1978: Introduced VaisaJ.a RS21 radiosondes with factory-built ground equipment. 1 Feb. 1985: Introduced VaisaJ.a RS80 radiosondes and Omega windfmding with MicroCORA ground equipment. Coded message no longer generated by KNMI mainframe computer. Significant levels no longer selected manually. Introduced new radiation corrections provided by VaisaJ.a. Stopped the practice of omitting humidity data above 300 hPa or when temperatures were lower than -40°C. 28 April1985: Changed observation times to 0000, 0600, 1200 and 1800 UTC. 1 April1988: Introduced VaisaJ.a RS80-15N radiosondes and Omega windfmding with DigiCORA ground system.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Radiosoundings have been made routinely only at De Bilt (06260), at the same location since 1947.

V. PUBLICATIONS

De Jong, H.M., 1961: On the possibility of improving aerological observations by using synchronous radiosonde and radar data and on a new aerological diagram. Scientific Report W.R. 61-3, Royal Netherlands Meteorological Institute, de Bilt.

De Jong, H.M., 1984: On the monitoring of the meteorological quality of upper-air observations and critical notes on some regulations in the PILOT and TEMP codes. Memorandum DM-84-07, Royal Netherlands Meteorological Institute, de Bilt.

53 W. NATIONAL EXPERT

Wim A.A. Monna; Royal Netherlands Meteorological Institute (KNMI); P.O. Box 201; 3730 AB de Bilt; The Netherlands; TEL: 31 30 20 69 11

54 NEW ZEALAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 10 June 1991)

Vaisala RS80-15 radiosondes at Tarawa (91610), Funafuti (91643), Kaitaia (93012), Paraparaumu Aerodome (93417), and Invercargill Aerodome (93844). At Tarawa and Funafuti, Vaisala PTU Processor PP11 's are used, and at the other three stations Vaisala PC-CORA ground stations are used. Vaisala RS80-15N radiosondes and DigiCORA ground stations at Campbell Island (93944), Chatham Island (93986), and Raoul Island (Kennadecs, 93997).

One observation daily at 0000 UTC at Tarawa, Funafuti, Chatham Island and Raoul Island (Kermadecs). Two observations daily at 0000 and 1200 UTC at Kaitaia, Paraparaumu Aerodrome, lnvercargill Aerodome and Campbell Island.

The Vaisala ground check set GC 22 is used at all stations.

At Tarawa and Funafuti, sounding data are analyzed and coded manually according to WMO recommendations except that the following levels are coded as significant in part TIBB of the TEMP message: (1) The highest level at which the temperature is 0.0°C. (2) The level of the coldest temperature. (3) A level between 300 and 200 hPa, if one is not selected according to the normal criteria. (4) A level between -37°C and -40°C, if one is not selected according to the nonnal criteria. After the sounding reaches this point, the relative humidity is no longer reported.

At Tarawa and Funafuti Vaisala Dew Point Slide Rules Type ABDS 11 are used to calculate dewpoint for the standard-level data.

The only current reporting practice at the DigiCORA and PC-CORA stations different from WMO FM 35-IX regulations is the coding of the highest level at which the temperature is 0.0°C as a significant level in part TIBB of the TEMP message.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

The following dates are approximate. See microfiche Appendix 4 for station-specific information.

Radiosondes: 1943-1960: Bendix-Friez AN/AMQ-1 (or model 271-2) or Eclipse Radio Diamond Hinman radiosondes. 1960-1979: Astor or VIZ (various models) Diamond Hinman-type radiosondes, without solar corrections. 1979-1989: VIZ 1395 series or Philips (Australia) RS4 Model I, II ,or m, Diamond Hinman type, not solar corrected. 1989-: Vaisala RS80-15, used with Vaisala PTU Processor PPll, with solar radiation corrections.

55 Thermistors: Oct. 1960: Introduced exposed thermistor radiosondes with ML 419 thermistor made by Moulded Insulation Co. (USA) progressively to replace duct-type radiosondes. The ML 419's were in use until at least 1965. Mid to late 1980's: VIZ rod-type, white-coated thermistor Part Nos. 1166-211, 1166-111, and 1166-311 were in use.

Hygristors: 1981: Introduced carbon hygristors to replace lithium chloride hygristors, except at Campbell Island where carbon hygristors were introduced in 1960. 1984: Humidity sensors used in the VIZ and Philips RS4 (403 MHz) radiosondes were VIZ #1186- 161.

Methods of Observation: 1960: Probably introduced a baseline check using aspirated chamber equipped with a psychrometer and a tray of saturated sodium chloride solution. (Calcium chloride granules were used after about 1980.) 1965: Introduced an improved check chamber, which was used until introduction of VaisaHi radiosondes. Nov. 1974: Began making observations 1 hour earlier than Standard Time due to daylight savings observance in New Zealand at the following stations: 93012, 93119, 93337, 93417, 93780, 93844, 93944, 93986, and 93997. Start and finish dates of the periods are included in microfiche Appendix 4.

Data Reporting: 1 Oct. 1948: Ceased applying temperature corrections given in the instructions for Bendix-Friez ANIAMQ-1 radiosondes to readings from those radiosondes and Australian radiosondes. 1943-59: Used vapor pressure tables in U.S. Weather Bureau Instructions for Radiosonde Observations, Circular P, 5th edition, or a wooden slide rule, possibly from the British Meteorological Office. 1959-68: Used mixing ratio calculator, U.S. Navy ML-326/UM. When dewpoint depression was less than -40°C, tables in the New Zealand Meteorological Service Manual were used. 1968-86: Any of the following three methods for dewpoint depression were used: (1) Nomograms in New Zealand Meteorological Service Instruction Manual that correspond to WMO Meteorological Table 4.21 (1973). (2) Vaisala Dew Point Slide Rule Type ABDS 11. (3) Mixing ratio calculator, U.S. Navy ML-326/UM. 1986- : Employed DigiCORA and PC-CORA algorithms or Vaisala Dew Point Slide Rule Type ABDSll.

In April1974 and Aug. 1988, changes were made in the method of reporting dewpoint depression when the humidity signal was "motorboating" (ordinate values less than 5%).

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

56 IV. STATION HISTORIES

See microfiche Appendix 4.

V. PUBLICATIONS

Alien, R.L. and J.F. De Lisle, 1965: Mean day-night stratospheric temperature differences in the New Zealand area found by exposed radio thermistor radiosonde. New Zealand J. Sci., .8.(3).

de Lisle, J.F., 1963: Summaries of radiosonde data 1956-1961. New Zealand Meteorological Service Miscellaneous Publication 119, 40 pp.

Gabites, J .F., 1953: Temperatures in the troposphere and lower stratosphere over the New Zealand region. New Zealand J. Sci. Technol..

Ogilvie, I.M., 1984: Effect of temperature on non-compensated radiosonde baro-units of Australian manufacture. New Zealand Meteorological Service Circular Note No. 49.

Tomlinson, A.I., 1975: Upper air statistics for New Zealand stations (1957-1973): New Zealand Meteorological Service Miscellaneous Publication 147, 129 pp.

Uddstrom, M.J., 1984: Solar radiation corrections for New Zealand and Australian radiosondes. New Zealand Meteorological Service Scientific Report No. 6.

Uddstrom, M.J., and D.K. Pumell, 1989: Real time data quality control and monitoring in the New Zealand Meteorological Service. Presented at the WMO Workshop on Data Quality Control Procedures, Reading, 6-10 March 1989.

VI. NATIONAL EXPERT

Ralph Pannett; Manager, Information Systems; New Zealand Meteorological Service; P.O. Box 722; Wellington, New Zealand; TEL: 64 04 729-379

57 PAKISTAN

I. CURRENT INSTRUMENTS AND PRACTICES (As of 14 January 1991)

ViiisaHi RS80-15 radiosondes. One observation daily at 0000 UTC. Humidity is generally not reported above 250 hPa.

I/. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Complete listings for each station are included in the microfiche Appendix 4. Generally applicable changes are as follows:

1957-1960: Metox radiosondes. 1960-1962: U.S. Weather Bureau radiosondes. 1962-1965: Philips radiosondes. 1965-1968: Autovox radiosondes. 1968-1969: Meisei radiosondes. 1969-1975: Astor radiosondes. 1975-1977: VIZ radiosondes. 1977-1985: VIZ radiosondes (?). 1985- : VIZ 1495 (?) and Viiisala RS80-15 radiosondes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Available through Office Record. See microfiche Appendix 4.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Ghulam Farid; Director Meteorological Services; Government of Pakistan; Pakistan Meteorological Department; Meteorological Complex; University Road. Headquarters Office; P.O. Box N0:8454 Karachi-32; Pakistan

58 PHILIPPINES

I. CURRENT INSTRUMENTS AND PRACTICES (As of 13 May 1991)

Viiisiilii RS18 radiosondes and Windsonde WS13/18 used for upper-air observations at Mactan. Viiisiila Automatic Radiosonde Receiver Type AR16 and RT18 radiotheodolite for daily rawinsonde observations at Mactan (98646). Vaisiila RS80 radiosondes and MicroCORA at Laoag. Observations once daily at either 0000 or 1200 UTC, more frequently during special experiments or tropical storms that might affect the Philippines. Humidity data conversion made with Viiisiila Dew Point Slide Rule.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1954-1968: Bendix radiosondes and GMD ground equipment. 1959: Suspended upper-air observations. 1961: Introduced Viiisiilii RS21 radiosondes at Zamboanga and Laoag. 1975: Introduced Viiisiila Automatic Radiosonde Receiver Type AR13 with Windfmding Instrument Type RT18 at Lahug·, Cebu City. Manual tracking at Zamboanga and Laoag. 1977: Viiisiilii Automatic Radiosonde Receiver Type AR16 at Mactin and Laoag. AR 13 moved from Mactin to Zamboanga. 1984: Introduced Viiisiilii RS80 radiosondes and MicroCORA at Laoag. Feb. 1991: AR 16 equipment from Laoag installed at Peurto Prinsesa, paired with windfmding equipment of that station. NOTE: Peurto Prinsesa and Davao use American windfmding radar.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

TV. STATION HISTORIES

See microfiche Appendix 4 for station-specific information.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Claro S. Doctor; Chief, Field Operation Center; Republic of Philippines; Department of Science and Technology; Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA); ATB Building 1424 Quezon Ave.; Q.C.; Philippines; TEL: 922:-84-01 to 10

59 POLAND, REPUBLIC OF

I. CURRENT INSTRUMENTS AND PRACTICES (As of 26 November 1990)

MARS-2-2 radiosondes and Meteorit-2 radar tracking system. For temperatures less than -40°C, no humidity data are reported. See Section 4 for dewpoint depression algorithm.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Approximate dates of generally applicable systems are listed below. Exact dates of changes differ from station to station. See microfiche Appendix 4.

Instruments: 1948-62: Lang radiosondes with radioreceiver. 1961-64: Metox radiosondes with Metox radiotheodolite. 1960's: A-22-ID radiosondes with Metox radiotheodolite. 1964-1971: RM-12 radiosondes with Metox radiotheodolite. 1970-90: A-22-IV radiosondes with Metox radiotheodolite. 1970's-1982: RKZ-2 radiosondes with Meteorit-1 radar. 1977-1987: RKZ-5 radiosondes with Meteorit-2 radar. 1987- : MARS-2-2 radiosondes with Meteorit-2 radar

Data Conversion Techniques: Unti11970: Dewpoint determined from psychrometric tables (Rojecki, 1959). 1971: Started to report humidity data only to 200 hPa. 1975: Introduced semiautomatic calculations with programmed calculator. 1985: Introduced microcomputer systems. 1988: Introduced personal computer systems.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

See microfiche Appendix 4.

V. PUBLICATIONS

Manuals of Observation for each radiosonde, issued in Polish for internal use by the Institute of Meteorology and Water Management (Polish Meteorological Service), are available upon request.

Rojecki, A., 1959: Tablice psychrometryczne. Seria A. Instrukcje i podreczniki Nr 41, PIH-M, Warszawa.

60 V1. NATIONAL EXPERT

Zenobia Litynska, Manager of Aerology Dept., Institute of Meteorology and Water Management, Podlesna 61, 01-673 Warsaw; Poland

61 REPUBLIC OF KOREA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 30 November 1990)

VIZ model1524-511 Microsondes, precalibrated at the factory, with Omega windfmding and fully automatic minicomputer system. Radiosondes are manufactured by Korean Jinyang Co., by agreement with VIZ. Upper-air observations currently carried out by W0-2000AT automatic observation system twice daily at 0000 and 1200 UTC, four times daily at Osan (47122). Dewpoint depressions calculated by automatic observation system. No corrections applied to temperature or humidity data.

//.PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: Nov. 1965: Introduced VIZ 1392 series radiosondes and radiotheodolite. 1987: Introduced VIZ model 1524-511 Microsondes and fully-automatic minicomputer-based system.

Observation Times: The following changes are applicable to Osan (47122). June 1977: Changed from 0000 and 1200 UTC to 0000, 1200, and 1800 UTC. 1985: Changed to 0000, 0600, 1200, and 1800 UTC. Nov. 1986: Changed to 0000 and 1800 UTC. March 1987: Changed to 0000, 0600, 1200, and 1800 UTC.

Data Reporting: Practices based on WMO International and Region-IT technical regulations. Oct. 1956: For temperatures lower than -40°C or relative humidity below 10%, humidity reported as missing (I I in coded message). 1987: Began reporting all humidity data, except at two stations (47122, 47158) that still report I I in coded message as described above.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

N. STATION HISTORIES

Annual general reports, in Korean, have station history information. Microfiche Appendix 4 includes location change for one station, Chejudo (47187, 47185).

V. PUBLICATIONS

Vl. NATIONAL EXPERT

Kim, Seung-Han; Director-General; Planning Bureau; Korea Meteorological Service; 1 Songwol dong, Chongno-gu; Seoul110-101, Korea; TEL: (02) 737-0011-17

62 ROMANIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 19 November 1990)

A-22-IV radiosondes, calibrated at the factory, with Malahit radiotheodolite. Two to four soundings daily. Data are checked manually for errors. Soundings are compared with the previous sounding and with soundings from other stations. Graphical method is used to compute dewpoint depression.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1942-49: Lang radiosondes. 1950-58: Moltchanov radiosondes. 1959- : A-22-m and A-22-IV radiosondes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

At Bucarest (15420), MRZ-3A radiosondes and the AVK-1 system will be used. At Cluj-Napoca (15120) and Constanza (15480), the AVK -1 system or a Vaisala system will be used. Automation of data processing is planned.

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT loan Milo~; Ministere de l'Environement; Institut de Meteorologie et Hydrologie; Sos. Bucure~ti Ploie~ti No. 97; 71581 Bucarest 18; Romania

63 SAUDI ARABIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 27 November 1990)

VaisaHi RS80-15N radiosondes and MicroCORA ground system. Ground calibration of sensors made before launch. No corrections are applied to temperature or humidity data. (?)

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1964-68: Vaisa.Ia RS13 radiosondes with radiotheodolite. 1969-72: Vaisa.Ia RS15 radiosondes and Windsonde WS15. 1973-78: Vaisa.Ia RS18 radiosondes and Windsonde WS18. 1978: Stopped using humidity cutoffs. Previously, dewpoint was not reported for temperatures below -40 °C. · 1977-82: Vaisa.Ia RS21-12CN radiosondes with CORA ground system. 1983- : Vaisa.Hi RS80-15N radiosondes. 1986: Began gradual introduction of helium, to replace hygrogen gas in balloons. All stations had been changed by December 1988.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

Included in Annual Environmental and Climatological Report, and in the Climatology Data Catalogue.

V. PUBLICATIONS

A basic history of radiosonde systems will be introduced into future upper-air data publications.

W. NATIONAL EXPERT

Abdulkarim M. Henaidi; Director, Climate Department; Kingdom of Saudi Arabia; Ministry of Defense and Aviation; Meteorological and Environmental Protection Administration; P.O. Box 1358 Jeddah 21431; Saudi Arabia

64 SEYCHELLES

I. CURRENT INSTRUMENTS AND PRACTICES (As of 15 November 1990)

Vaisala RS80-15 radiosondes. For temperatures below -40°C, relative humidity is reported as missing. Radiation corrections are applied to temperatures using Radiation Correction Table RSN 86 for Vaisala Radiosonde RS80. No corrections are applied to humidity data. One observation daily at 1115 UTC.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

July 1983: Introduced Vaisala RS80-15 to replace Vaisala RS21 radiosondes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

Patrick M. Bijoux; Directorate of Civil Aviation; P.O. Box 181; Seychelles International Airport; Mahe, Seychelles

65 SINGAPORE

I. CURRENT INSTRUMENTS AND PRACTICES (As of 8 December 1990)

Vaisala RS-80 radiosondes with MicroCORA ground system.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments and Data Reporting Practices: Aug. 1954: Kew Mark liB radiosondes. Applied radiation and lag corrections to temperature data. Discarded humidity readings above 300 hPa. Sept. 1956: Fully-automatic ground receiver equipment in use. 1959: For temperatures below -40°C, relative humidity was discarded. Significant temperature levels were based on departure of more than 1 °C below 500 hPa and 2°C above 500 hPa from linear interpolation between adjacent levels. Significant humidity levels were based on departure of more than 10%. 1964: Changed criterion for significant humidity levels to 15%. March 1971: Introduced Astor Type 403 radiosonde. No corrections recommended by manufacturer. Jan.-Apri11972: Used both Kew Mark liB and Astor Type 403 radiosondes May 1972: Began using Astor Type 403 only. July 1973: Introduced Astor Type RS4 radiosondes. No change of sensors. 1978-79: Introduced Vaisala RS21-12C radiosondes. Introduced correction of temperature data for solar radiation effects.

Observation Time: Aug. 1954-0ct. 1955: 0300 UTC observations. Nov. 1955-July 1956: No observations. Aug. 1956: Resumed 0300 UTC observations. Apri11957: Changed to 0000 UTC observations. May 1967: Introduced an extra ascent at 1100 UTC. Dec. 1984: Night ascent changed to 1000 UTC to meet local forecast requirements. ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

The feasibility of using wind profllers is being examined.

IV. STATION HISTORIES

V. PUBLICATIONS

See microflche Appendix 4 for copies of Introductory Notes from annual Uwer-Air Data reports for additional information regarding observations, data reporting, etc.

66 VI. NATIONAL EXPERT

K. Thulasidas; Meteorological Service Singapore; P.O. Box 8; Singapore Changi Airport; Singapore 9181; Republic of Singapore; TEL: 5457194

67 SOLOMON ISLANDS

I. CURRENT INSTRUMENTS AND PRACTICES (As of 26 November 1990)

VaisaHi radiosondes.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1 Dec. 1986: Introduced Vaisala radiosondes to replace Philips radiosondes.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

No change in station location since 1950.

V. PUBLICATIONS

All upper-air data are processed and archived by the Australian Bureau of Meteorology.

VI. NATIONAL EXPERT

F. Ahiku; Solomon Islands Meteorological Service; Ministry of Tourism and Aviation; P.O. Box 2l Honiara; Solomon Islands; TEL: 21757/58/59

VII. MISCELLANEOUS INFORM__ATION

Information from Australia regarding observation methods is pertinent to the Solomon Islands.

68 SOUTH AFRICA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 21 December 1990)

Vaisala RS80-16 radiosondes at most stations and RS80-15N at Irene, Port Elizabeth, Gough Island, and Marion Island. Currently 14 stations are in operation, including the Antarctic base S.A.N.A.E.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Various Vaisa.Ia radiosondes have been used since the 1960's, with the exception of a short period of time in the 1970's when Weathermeasure radiosondes were used.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Planned conversion of four to six more upper-air stations to Vaisii.lli RS80-15N in early 1991.

N. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

I. M. Nigrini; The Weather Bureau; Department of Environment Mfairs; Building; 159 Struben St.; Private Bag; Pretoria; South Mrica

VII. MISCELLANEOUS INFORMATION

This information was obtained through personal contact, not through WMO channels.

69 SUDAN

I. CURRENT INSTRUMENTS AND PRACTICES (As of 11 December 1990)

Vii.isiilii radiosondes with DigiCORA ground system. Observations at 1200 UTC daily at Khartoum, every 2 days at other stations.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

October 1990: Introduced Vii.isala DigiCORA ground systems to replace earlier manual Vii.isala systems.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Introduction of DigiCORA ground systems will be continued in 1991.

IV. STATION HISTORIES

1952: Began operations at Khartoum. 1960: Began operations at Malakal. 1962: Began operations at Port Sudan. 1972: Began operations at El Fasher. 1973: Began operations at Dongola.

Some additional information is available in manuscript form.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Muzamil Abdelrahman; The Republic of the Sudan; Meteorological Dept.; P.O. Box 574 Khartoum; Sudan; TEL: 72992; TEL: 33088

70 SWITZERLAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 12 December 1990)

SRS-400 radiosondes. Relative humidity less than 10% is reported as 10% . See Section 4 for dewpoint depression algorithm.

Il. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Radiosondes: 1942-44: Swiss Sonde Model I. 1945-June 1946: Swiss Sonde Model Ia. July 1946-June 1947: Swiss Sonde Model IT. July 1947-June 1961: Swiss Sonde Model ID. 1979: Introduced electric motor to replace clock movement. 1 Apri11990: Introduced SRS-400.

Sensors on Swiss Sonde Models I, la, Il, and Ill: 1962-31 March 1990: Temperature sensor was bimetallic spiral. 1942-1971: Pressure sensor was a pair of aneroid capsules. 1971-31 March 1990: Pressure sensor was a double pair of aneroid capsules. 1942-59(?): Humidity sensor was hair hygrometer. 1959(?)-31 March 1990: Humidity sensor v; ;oldbeater's skin.

Tracking Systems: 1942-52: See references in microfiche Appendix 4. 1953-63: Metox radiotheodolite. 1963-69: Secondary radar "Repondeur". 1969-90: Meteolabor secondary radar.

Observation Times: 1942-47: Trial period, variable times. 1948-51: Workdays at about 0500 UTC. 1952-53: Workdays at about 1600 UTC. 1954-31 March 1957: Daily at 0200 and 1600 UTC. 1 Apri11957-3 Jan. 1982: Daily at 0945 and 2145 UTC. 4 Jan. 1982- : Daily at 1100 and 2300 UTC. ·

Calibration: 1959: Started making calibrations in air. 1962: Started making temperature calibration in silicon oil and humidity calibration at ambient temperature.

71 Data Conversions and Transmission: 1959(?)-31 March 1990: Correction made for goldbeater's skin humidity sensor lag for increasing relative humidity. 1972: Introduced pressure correction. 1972-30 April1980: Radiation corrections made to temperature data. 5 July 1975-18 May 1976: Due to programming error, soundings were approximately 0.7°C too cold. 18 May 1976-1 May 1980: Temperature correction in place. 14 Sept. 1978: Introduced practice of not reporting humidity at pressures less than 200 hPa. 1 May 1980-13 May 1980: New pressure and temperature corrections. 13 May 1980-30 April 1990: New temperature corrections. 1 1 May 1984: Changed value of gravitational acceleration from 9.8 to 9.80665 m s- • 1 April1990: Introduced new dewpoint depression algorithm. See Section 4.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

1991: Planned acquisition of BASORA 400C ground station. 1991: Planned implementation of radiation correction to temperature data.

IV. STATION HISTORIES

Station elevation changes: 1942-47: 483 m. 1948-54: 493 m. 1955- : 491 m

V. PUBLICATIONS

Ackermann, P., 1968: Die neue Radiosondenstation Payeme der Schweizerischen Meteorologischen Zentralanstalt. Publication de l'lnstitut Suisse de Meteorologie no 12.

Billwiller, R.: Die bisherige un zukiinftige Mitarbeit de Schweiz an der aerologischen Forschung.

Hoegger, B., A. Heimo, G. Levrat, and J. Rieker, 1989: SRS-400- The new Swiss radiosonde, Fourth WMO Technical Conference on Instruments and Methods of Observation, TECIMO-IV, 4-8 September 1989, Brussels, Instruments and Observing Methods Rwort No. 35, World Meteorological Organization, Geneva, 197-202.

Lugeon, J., 1941: Le poste aerologique de la station centrale de la meteorologie aPayeme et les nouvelles methodes suisses de radiosondages. Annalen de Schweizerischen Meteorologischen Zentralanstalt.

Lugeon, J., 1942: Hohenintegrator. Meteorologischen Zeitschrift, Heft 1, 12-19.

Lugeon, J., 1942: Quelques innovations aux methodes suisses de radiosondages. Annalen de Schweizerischen Meteorologischen Zentralanstalt.

72 Lugeon, J., 1959: L'echosondage de !'atmosphere. Annales de la Station Centrale Suisse de Meteorologie.

Lugeon, J., and P. Ackermann, 1948: La radiosonde suisse. Annalen de Schweizerischen Meteorologischen Zentralanstalt.

Reicker, J., 1984: Controle de l'efficacite de la correction de temperature de rayonnement du sondage aerologique de Payerne, appuye par les donnees de la compagne SOP du programme ALPEX. Rapport de travail No 126 de l'Institut Suisse de Meteorologie, 16 pp.

Richner, H., and P.D. Phillips, 1981: Reproducibility of VIZ radiosonde data and some sources of error. J. Appl. Meteor., 20, 954-962.

Ruppert, P., 1979: Das Radiosondierungssystem BASORA 400. Schwiezerische Technische Zietschrift, Nr. 15, 942-948.

These, and other publications listed in the microfiche Appendix 4, may be obtained from Bibliotheque de l'Institut Suisse de la Meteorologie; Kriihbiihlstrasse 58, Postfach, CH-8044, Zurich.

Vl. NATIONAL EXPERT

Jean Rieker; Le Chef, Station aerologique; Institut Suisse de Meteorologie; Les Invuardes; CH- 1530 Payerne; Switzerland

Vli. MISCEllANEOUS INFORMATION

Historical Events: 6 Aug. 1940: "Poste aerologique" created. 23 Dec. 1941: First balloon launch at Payerne. 13 June 1942: Radiosoundings began. 8-30 May 1950: First International Radiosonde Comparison. 22 May-22 June 1956: Second International Radiosonde Comparison. 9-20 Oct. 1978: National Radiosonde Comparison (ASOND-78). 13-29 Apri11981: Regional Radiosonde Comparison (SONDEX-81).

73 THAILAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 25 March 1991)

At stations 48327, 48455 and 48568, Metox radiosondes (tracked by radiotheodolite) and Vaisala radiosondes (with Omega tracking) are used alternately at 0000 and 1200 UTC. At station 48407 Metox and AIR radiosondes are used alternately at 0000 and 1200 UTC. At station 48565, only AIR radiosondes are used. Radiosondes are precalibrated at the factory. Humidity data are not reported for relative humidity below 10% or temperatures below -40°C. A slide rule is used to convert relative humidity to dewpoint depression.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

1981: Observations at 0000 and 1200 UTC. 1987: Changed from completely manual system to time-share computer system for calculating upper-air data.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

1990: Observation times will expand to comply with SPECTRUM '90.

IV. STATION HISTORIES

Histories are being compiled by the Meteorological Department of Thailand. Information for 1931- 1980 is out of print.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Damras Chongdarakul; Meteorological Department; 612 SukumvitRd.; Bangkok 10110; Thailand; TEL: Bangkok 2580437-9 (or) 2587057

74 TUNISIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 20 December 1990)

Vaisala RS80 radiosondes at both Carthage (60715) and Tozeur (60760).

Il. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Dates are approximate.

Instruments: Carthage: 1962: Metox radiosondes with manual tracking. 1964-73: Vaisiila RS13, RS15 radiosondes with manual tracking. 1973-78: Vaisiila RS18 radiosondes with manual tracking. 1978-82: Vaisiila RS21 radiosondes with CORA ground system. 1989- : Vaisiila RS80 radiosondes with DigiCORA ground system.

Tozeur: 1967: Began operations with Vaisiila RS15 radiosondes with manual tracking. 1980: Introduced Vaisiila RS18 radiosondes with manual tracking. 1989: Introduced Vaisala RS80 radiosondes with DigiCORA ground system.

Observation Practices and Times: 1962-88: 1100 and 2300 UTC. 1988- : 2300 UTC only. 1978: Began reporting humidity data for the entire sounding. Previously, no humidity data were reported for pressures less than 300 hPa.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

H. Trabelsi; Le Representant Permanent de la Tunisie aupres de l'OMM:; Ministere du Transport; Institut Nationale de la Meteorologie; B.P. 156-2035; Tunis-Carthage; TEL: 782400

75 UNION OF SOVIET SOCIALIST REPUBLICS

I. CURRENT INSTRUMENTS AND PRACTICES (As of 1 February 1991)

A-22 radiosondes tracked with Malahit radiotheodolite at six stations. MARS-2-1 radiosondes tracked with Meteorit-1 secondary radar at 22 stations and on 12 ships. MARS-2-2 radiosondes tracked with Meteorit-2 secondary radar at 87 stations. MRZ-3A radiosondes with AVK -1 ground stations at 98 stations. Viiisiila CORA or MicroCORA systems on six ships. All radiosondes are precalibrated at the factory. Solar radiation corrections are applied to temperature data. See Ivanov et al. (1991) in Section 6.2 for details. At stations where MARS data are manually processed, humidity data are not transmitted for temperatures below -40°C and dewpoint depression is determined using a graphical scale. At stations with automatic data processing, dewpoitlt depression is calculated. See Section 4 for algorithm.

11. PAST CHANGES IN INSTRUMENTS AND PRACTICES

30 January 1930: First radiosonde launch in USSR. 1934: Introduced RZ-049 radiosondes, tracked by optical theodolite. 1937: Began routine upper-air observations. 1955-57: Introduced A-22 radiosondes and Malahit radiotheodolite. 1957-59: Introduced RKZ-1A radiosondes and Meteorit-1 secondary radar. 1957: Began systematic Arctic observations. 1961: Began shipboard observation program. 1962: Introduced radiation corrections to temperature data. 1967: Introduced improved thermistor (with a new white coating) to RKZ radiosonde. 1971: Introduced RKZ-5 radiosondes and Meteorit-2 secondary radar. 1974: Introduced semiautomatic processing system. 1976: Introduced fully-automatic processing system at (about 25) Meteorit-RKZ stations only. 1983-84: Introduced MARS radiosondes. 1986: Introduced MRZ-3A and secondary radar system A VK-1 (Aerological Computing Complex), with fully-automatic processing. 1986: Introduced practice of not reporting humidity data for temperatures below -40°C at stations where MARS data are manually processed.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

A new radiosonde will be introduced in 1992-93.

N. STATION HISTORIES

Stations histories have been maintained and are currently being compiled.

76 V. PUBLICATIONS

Central Aerological Observatory, 1966: Handbook for Hydrometeorological Stations and Posts: Issue 4. Upper-air Observations: Part m. The Temperature and Wind Radiosounding by the Malahit-A-22, Gydrometeoizdat, Leningrad.

Central Aerological Observatory, 1973: Handbook for Hydrometeorological Stations and Posts. Issue 4. Upper-air Observations: Part ma. The Temperature and Wind Radiosounding by the Meteorit-RKZ. Gydrometeoizdat, Leningrad, 256 pp.

Central Aerological Observatory, 1974: Handbook for Hydrometeorological Stations and Posts. Issue 4. Upper-air Observations: Part m-b. The Temperature and Wind Radiosoundinng by the Meteorit-RKZ on Ships, Gydrometeoizdat, Leningrad, 130 pp.

Efnnov, P.L., 1962: The principles of a rational space distribution of the upper-air network. Transactions (Tr.) of Central Aerological Observatocy (CAO), 43, 3-10.

Efnnov, P.L., and A.M. Khachatryan, 1959: Accuracy of wind speed and direction measurements by the radiotheodolite 11 Malakhite.,. Tr. CAO, 31, 83-92.

Fridson, M.B., 1989: The estimation of the errors in temperature and humidity measurements by radiosondes of the uppper-air network of the USSR. Meteor. Gidrol. , ~' 114-118.

Fridson, M.B., and V .I. Shlyakhov, 1971: On some peculiarities of temperature measurements by radiosondes at high atmospheric levels. Tr. CAO, 102, 130-138.

Krechmer, M.V., 1966: The errors of wind measurements due to innacurate coordinate measurements. Tr. CAO, 74, 3-23.

Marfenko, O.V., 1957: Random errors of radiosonde RZ-049. Tr. CAO, 22, 35-40.

Marfenko, 0. V., 1962: Random errors of the meteorological elements measurements in the free atmosphere by radiosondes A-22-m, RKZ-1A. Tr. CAO, 43, pp. 35-42.

Marfenko, O.V., 1963: The accuracy of the temperature-wind sounding of the atmosphere. Proceedings of the All-Union Meteorological Meeting, v. IX, 118-124.

Marfenko, O.V., 1969: The estimation of the radiosounding accuracy at the upper-air network of the USSR. Meteor. Gidrol., .3., 14-21.

Marfenko, O.V., 1971: Errors of temperature measurements of RKZ-2 radiosonde and method of operation. Tr. CAO, 102, 11-19.

Marfenko, O.V., and K.I. Merkelova: Results of the investigation of the radiation errors of radiosonde RKZ with the thermistor MMT-6 in flight conditions. Tr: CAO, 67, 24-31.

77 Marfenko, O.V., and K.I. Markelova, 1966: Results of the investigation of battery tension influence on temperature measurements by radiosonde RKZ-1A. Tr. CAO, 74, 23-28.

Pokrovskiy, V.N., and S.M. Shmeter, 1955: The ra,diation influence on cylindrical temperature sensors. Tr. CAO, 14, 23-32.

Pokrovskiy, V.N., and S.M. Shmeter, 1955: Radiation errors of a comb (RZ-049) radiosonde, Tr. CAO, 14, 32-44.

Reshetov, V.D., 1953: The instructions of pressure maps used for analysis of upper-air data quality. Guidebook CAO, 13, 3-7.

Reshetov, B.D., 1953: The base of analysis of wrong radiosounding data revealed on upper pressure level maps. Guidebook CAO, 13, 7-14.

Reshetov, V.D., 1958: On the radiation overheating of a comb radiosonde and its influence on radiosounding data. Tr. CAO, 24, 59-72.

Semina, N.A., 1962: On absolute methods for determination of radiation errors for radiosondes. Tr. CAO, 43, 31-35.

Shlyakhov, V .I.: The current state and perspectives of a wind-temperature and special radiosounding. Tr. CAO, 90, 5-16.

Shmeter, S.M., 1954: Inertial errors of air temperature measurements by radiosonde. Tr. CAO, 13, 60-73.

Shmeter, S.M., 1954: Random errors of temperature and pressure measurements by comb radiosondes (RZ-049) in the free atmosphere. Tr. CAO, 13, 46-69.

Zaichikov, P.F., 1956: The method of threefold control and its application for the investigations of radiosonde accuracy. Tr. CAO, 16, 10-18.

Zaichikov, P.F., 1962: The method of definition of radiation corrections for temperature data of radiosondes A-22-ID, RKZ-1 and RZ-049 on the basis of temperature differences (day minus night). Tr. CAO, 43, 10-22.

Zaichikov, P.F., B.P. Zaichikov, and M.B. Fridson, 1976: The investigation of a heat wake of balloons. Tr. CAO, 118, 28-32.

Zaichikov, P.F., and O.V. Marfenko, 1957: Reshetov method of radiation corrections determination for radiosonde RZ-049 temperature sensors. Guidebook CAO, 19, 36 pp.

Zaichikov, P.F., and O.V. Marfenko, 1971: Instrumental errors of pressure sensors of radiosondes A-22-IV and A-22-ill. Tr. CAO, 102, 24-30.

78 Zaichikov, P.F., O.V. Marfenko and others, 1968: Radiation corrections for radiosonde A-22 and RKZ (values and methods). Guidebook CAO, 38, 50 pp.

Zaitseva, N., 1990: Aerologica, Gidrometeoizdat, Leningrad, 325 pp. (In Russian and in English translation.)

VI. NATIONAL EXPERT

Nina Zaitseva; Central Aerological Observatory; 3, Pervomayskaya; Dolgoprodny, Moscow Region; 141700 Russia

79 UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND

I. CURRENT INSTRUMENTS AND PRACTICES (As of 19 July 1991)

Vaisiilii RS80-15 radiosondes with PC-CORA ground equipment. Winds obtained with Meteorological Office Windfmding Radar (MOWFR) MK4, auto-follow primary radar. Radiosondes are precalibrated, and there is a single ground check procedure prior to launch.

Il. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Dates refer to general implementation; more specific information is included in the microfiche Appendix 4.

Instruments: Stations in the U.K. : 1946: Introduced lJK MKII radiosondes. 1952: Introduced lJK MKIIb radiosondes. Double ground check was made for factory calibrated elements. 1977-78: Introduced lJK MK3 radiosondes. Double ground check was made for factory calibrated elements prior to launch. Wind data were derived from MOWFR MK4. Fully-automatic recording and computation of sounding. NOTE: Due to electrical problems detected later, data collected with the MK3 between 1979 and 1981 were inaccurate. Early 1990: Introduced Viiisiilii RS80-15 radiosondes with PC-CORA ground equipment. Winds obtained with MOWFR MK4, auto-follow primary radar.

Overseas Stations: Jan. 1948-Feb. 1968: Observations at Port Stanley, Falkland Islands, using lJK MKIIb radiosondes. March 1987: Began observations at Mount Pleasant, Falkland Islands, using Viiisiilii RS80-15 radiosondes and MicroCORA ground systems. Apri11977: Began observations at St. Helena using Viiisiilii RS21 radiosondes. Aug. 1986: Introduced Vaisiilii RS80 radiosondes at St. Helena. March 1979-May 1990: Graw M60 radiosondes (Gibraltar Grawsonde) at Gibraltar.

Ocean Weather Ships (particularly, OWS Lima): 1952: Introduced UK MKIIb radiosondes to replace UK MKII. June 1977: Completed introduction of Beukers/VIZ radiosondes with Loran windfmding. During the period Oct. 1976-June 1977, one ship maintaining the station used this system while the other ship used a radar wind system. Jan. 1986: Introduced Vaisala RS80-15N radiosondes.

Antarctic Stations: 1954-Feb. 1971: UK MKII radiosondes. Feb. 1971: Introduced Graw M60 radiosondes. March 1974: Introduced VIZ Locatesondes or Beukers equivalent.

80 Feb. 1984: Introduced Vaisalii RS80 radiosondes. See microfiche Appendix 4 for table to correct 1984-1987 data.

Data Reporting: 1 1 Jan. 1956: Changed computation units from feet (°FY to geopotential meters (°Cy • Introduced lag and solar radiation corrections. 1960: Began automatic recording of radiosonde data, with manual computations. Previously, both recording and computations were done manually. Feb. 1961: Introduced new radiation corrections. Oct. 1964: Began computing all ascents to balloon burst using radar heights instead of pressure. Previously, soundings were terminated at 30 hPa. Feb. 1965: Introduced refmed lag and solar radiation corrections.

Observation Times: Stations in the U.K. : Feb. 1952: Began making combined temperature/wind ascents at 0300 and 1500 UTC and wind only soundings at 0600 and 0900 UTC. Previous practice was four temperature/wind ascents daily at the nominal hours of 0300, 0600, 0900, and 1500 UTC. Apri11957: Sounding times changed to 0000 and 1200 UTC for temperature/wind soundings and 0600 and 1800 UTC for wind-only soundings. In general, the actual launch was 30 to 45 minutes before the hour.

Overseas Stations: Apri11957: Sounding times changed to 0000 and 1200 UTC. Previously, soundings were made at 1500 UTC and, nonregularly, at 0300 UTC.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

During 1991-92, Loran will replace primary radar windfmding at Crawley (03774), Aughton (03322), Shanwell (03170), and Long Kesh (03920). In Jan. 1992, AIR 4A radiosondes will replace Vaisala RS80 radiosondes at Halley, Antarctica.

IV. STATION HISTORIES

See microfiche Appendix 4 for a list of stations operated by the U.K. and some station history information.

V. PUBLICATIONS

Blackall, R.M., 1992: Some notes on radio sounding in the United Kingdom, Meteor. Mag., 121, 89-90.

Downes, C.R., 1977: History of British ocean weather ships. Marine Observer, Vol. XLVII.

Dymond, E.G., 1944: Humidity measurements with the Kew radiosonde, Meteorological Research Paper, No. 206, London.

81 Dymond, E.G., 1947: The Kew radiosonde. Proc. Phys. Society, 59, 645-666.

Edge, P., M. Kitchen, J. Harding, and J. Stancombe, 1986: The reproductibility of RS MK3 radiosonde and MOWFR MK4 radar measurements. OSM No. 35.

Harrison, D.N., 1944: Comparison of heights measured by radiosonde and GLill. Meteorological Research Paper, No. 203, London.

Harrison, D.N., 1948: The accuracy of :MKII radiosonde observations. Meteorological Research Paper, No. 422, London.

Harrison, D.N., 1948: The errors of GLill observations. Meteorological Research Paper, No. 387, London.

Harrison, D.N., 1962: The errors of the Meteorological Office radiosonde MK28. Scientific Paper Meteorological Office, No. 15.

Kitchen, M., and J. Nash, 1985: A Comparison of Wind Measurements by a Vaisala RS80-15N LORAN Wind Finding System and the UK Operational (MOWFR MKIV) Radar.

Meteorological Office, 1943: Meteorological Office Radiosonde. Measurement of Temperture and Humidity. London.

Meteorological Office, 1951: Measurement of Upper Winds, Report of Discussion, Meteorol. Mag., 80, 83-86.

Meteorological Office, Upper Air Summaries. 1946-50. MO 555.

Meteorological Office, Upper Air Summaries. 1946-50. MetO 910b.

Meteorological Office, Handbook of Weather Forecasting. Ch. 11, Sect. 3.

Meteorological Office, Handbook of Meterological Instruments. Pt. II, MO 577.

Ponting, J.F., J. Nash, and M. Kitchen, 1985: Operational evaluation of Navaid wind-fmding systems in the United Kingdom. Instruments and Observing Methods. Rtmort No. 22, WMO, 145- 150 World Meteorological Organization, Geneva.

Scrase, F.J., 1944: The errors of upper air temperature and pressure measurements. Meteorological Research Paper, No. 205, London.

Scrase, F.J., 1956: Application of radiation and lag corrections to temperatures measured with Meteorological Office radiosonde. Meteorol. Mag., 1005(85), 65-78.

Shanklin, J.D., 1989: Antarctic stratospheric temperature and ozone trends, Third International Conference on Southern Hemisphere Meteorology and Oceanography, 412-413.

82 VI. NATIONAL EXPERT

J. Nash; Head of Upper Air Section; Observation Provision Branch; Meteorological Office; Headquarters Annexe; Eastern Rd.; Bracknell Berkshire RG12 2UR; United Kingdom; TEL: 0344 (Bracknell) 855925

83 UNITED REPUBLIC OF TANZANIA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 31 October 1990)

Vais~ila RS18 radiosondes at Tabora (63832). Mesural MH-73A radiosondes at Dares Salaam (63894). One observation daily at 1200 UTC. For temperatures less than -40°C, humidity is reported as missing.

!I. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Instruments: 1958: British Kew Mark 1 radiosondes tracked by GL manually-operated receiver. 1966-84: Vaisala RS13, RS15, and RS18 radiosondes at Dares Salaam. 1976: Introduced windfmding radar WF to replace radiotheodolite at Dares Salaam. 1977: Established station at Tabora (63832) using Vaisala RS18 radiosondes tracked by WF 100. 1984: Introduced Mesural MH-73A radiosondes at Dares Salaam. 1986: Introduced windfmding radar WF 33 at Dar es Salaam.

Observation Times: 1958: 1200 UTC. 1966: 0000 and 1200 UTC. 1977: At Tabora, one observation at 1200 UTC. 1984-90: At Dares Salaam, one observation at 1200 UTC

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

Installation of Vaisala CORA system at Mtwara (63971) and Kigoma (63801).

IV. STATION HISTORIES

V. PUBLICATIONS

VI. NATIONAL EXPERT

M.M. Kavishe; Acting Director General; The United Republic of Tanzania Directorate of Meteorology; P.O. Box 3056; Dares Salaam; Tanzania; TEL: DAR 26231

84 UNITED STATES OF AMERICA

I. CURRENT INSTRUMENTS AND PRACTICES (As of 15 April1991.)

VIZ "B" model1492-520 radiosondes and MicroART (Automatic Radio Theodolite) ground system at most National Weather Service (NWS) stations. Space Data Division radiosondes and MicroART (Automatic Radio Theodolite) ground system at the remaining NWS stations. For relative humidity below 20% the dewpoint depression is reported as 80 in the coded message and 30 in the archived data. For temperature below -40°C, dewpoint depression is reported as missing. See Section 4 for dewpoint depression algorithm.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Notes: (1) The U.S. upper-air system includes stations run by the NWS (previously U.S. Weather Bureau), the U.S. Air Force (Air Weather Service), and the Navy. These networks have not always used the same instruments and practices.

(2) For many decades radiosondes have been procured from the VIZ Manufacturing Company. Appendix 3 is a listing of radiosonde models manufactured by VIZ.

1937: Established first operational U.S. radiosonde stations.

Radiosonde Instruments and Sensors: 1943: Introduced lithium chloride humidity element to replace hair hygrometer. Introduced ceramic temperature element, operating on resistance principle, to replace glass tubes with electrolytic temperature elements. 1946: Introduced white-coated thermistors at military stations. 1949: Introduced smaller ceramic temperature element to decrease instrument response time. 1958: Introduced radiosondes manufactured by VIZ at Weather Bureau stations. 1953-60: Gradually introduced white-coated and outrigger thermistors at Weather Bureau stations. 1960-62: Introduced carbon humidity element at military stations. 1963-66: Introduced carbon humidity element at Weather Bureau stations. 1972: Introduced redesigned carbon hygristor ducts to reduce solar radiation effects on instrument which were responsible for low biases in humidity measurements for some daytime soundings. 1980-81: Introduced prebaselined carbon hygristors (Accu-Lok) to VIZ radiosondes. 1986: Introduced Space Data Division (SDD) radiosondes and a new GMD-5 system at 5 Air Force stations. 1988-90: Introduced SDD radiosondes at selected NWS stations in the southwest United States and Alaska. VIZ radiosondes continued in use at other sites. 1988-89: Introduced VIZ "B" (Model1492-520) radiosondes to replace VIZ "A" (Model1492-510) radiosonde. 1988-89: Introduced MRS to 42 Navy ships and 6 Navy synoptic stations, all of which use the Vaisala RS80 radiosonde.

85 Tracking and Ground Systems: 1945-46: Introduced Signal Corps Radiodirection-fmder (SCR-658) manual electronic equipment to replace visual tracking methods. 1951: Introduced Ground Meteorological Direction-fmding (GMD-1) at Air Weather Service stations to replace SCR-658 tracking system. 1959: Introduced Weather Bureau Radio Theodolite (WBRT) at Weather Bureau stations to replace SCR-658. 1974: Introduced Automatic Radiotheodolite (ART) semiautomatic minicomputer-based system at NWS stations. 1985: Introduced MiniART, fully-automatic microcomputer-based system at NWS stations. 1989-90: Introduded MicroART system to replace MiniART system at NWS stations, but algorithms and level selection methods were not changed.

Observing and Reporting Practices: 1946: Began reporting data on constant pressure surfaces, instead of at constant heights. 1948: Changed observation times from 0400 and 1600 UTC to 0300 and 1500 UTC. 1948: Began computing all relative humidities using saturation values with respect to water. Prior computations involved saturation with respect to ice for temperatures below 0°C. 1950: Introduced radiation correction to temperature data between 400 and 10 hPa for daytime soundings whenever solar elevation angle was equal to or greater than -2.5°. 1957: Changed observation time from 0300 and 1500 UTC to 0000 and 1200 UTC. 1960: Discontinued radiation corrections. 1965: Began reporting low humidity measurements. (Earlier practice with lithium chloride sensor was to not report low values when the instrument was said to be "motorboating. ") 1969: Changed from completely manual system to a time-share computer system for calculating upper-air data. 1969: Introduced Billions (1965) algorithm for evaluating relative humidity. The algorithm was designed to match the "500 evaluator," in use since 1946. 1973: Introduced practice of reporting all relative humidities less than 20% as 19%. 1980-1981: Introduced VIZ evaluator 1286-065 (NWS 8002) for relative humidity.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

A new upper-air system is being planned. Before it is implemented, however, the following changes to the current radiosonde system are being considered:

Temperature: A new algorithm for temperature data. New temperature quality control techniques. Implementing solar and infrared radiation corrections to station data.

Humidity: Eliminating temperature and humidity cutoffs for humidity data. Correcting a low bias in relative humidity at values close to 100% .

86 Other: Inclusion of 925 hPa mandatory level per WMO request. Changing the gravity constant per WMO recommendation. A new hydrostatic check to prevent anomalous observations from being transmitted. Rectification of known software problems.

A complete list of "Proposed Changes to the Upper Air System in the 1990s" is included in microfiche Appendix 4. lY. STATION HISTORIES

Available through the National Oceanic and Atmospheric Administration, National Climatic Data Center, Federal Building, Asheville, NC 28801.

The following report also includes station histories for North American stations: Schwartz, B. E., and M. Govett, 1992: A hydrostatically consistent North American radiosonde data base at the Forecast Systems laboratory, 1946-present. NOAA Technical Memorandum ERL FSL ~. Available from NOAA/ERL/FSL, 325 Broadway, Boulder, CO 80303.

V. PUBLICATIONS

Air Weather Service, 1955: Accuracies of radiosonde data, Tech. Rep. 105-133, U.S. Air Force, Washington, DC, 12 pp.

Angell, J.K., W.P. Elliott, and M.E. Smith, 1984: Tropospheric humidity variations at Brownsville, Texas and Great Falls, Montana, 1958-80. J. Clim. Appl. Meteor., .2., 1286-1295.

Billions, N.S., 1965: Equations for computer processsing U.S. Weather Bureau radiosonde temperature and relative humidity data. Rep. No. RR-TN-66-3, U.S. Army Missile Command, Redstone Arsenal, AL, 35809, 6 pp.

Bosart, L.F., 1990: Degradation of the North American radiosonde network. Weather Forecasting, ~' 527-528.

Brousaides, F.J., and J.F. Morrissey, 1973: Residual temperature-induced humidity errors in the National Weather Service radiosonde, Part I. AFCRL-TR-73-0214. Instrumentation Papers No. 197, Air Force Cambridge Research laboratories, Bedford, MA 01730.

Brousaides, F.J., and J.F. Morrissey, 1974: Residual temperature-induced humidity errors in the National Weather Service radiosonde, Final report. AFCRL-TR-74-0111. Instrumentation Papers No. 215, Air Force Cambridge Research laboratories, Bedford, MA 01730, 35 pp.

Elliott, W.P., and D.J. Gaffen, 1991: On the utility of radiosonde humidity archives for climate studies. Bull. Amer. Meteor. Soc., 72, 1507-1520.

87 Elliott, W.P., M.E. Smith, and J.K. Angell, 1991: On monitoring tropospheric water vapor changes using radiosonde data. Greenhouse-Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations, M. Schlesinger (Ed.), Elsevier, Amsterdam, 311-328.

Friedman, M., 1972: A new radiosonde case: the problem and the solution. Bull. Amer. Meteor. Soc., 53, 884-887.

Hoehne, W.E., 1980: Precision of National Weather Service upper air instruments, NOAA Technical Memorandum NWS T&ED-16, Sterling, VA, 23 pp.

Jenne, R.L., and T.B. McKee, 1985: Data. Handbook of Applied Meteorology, D. Houghton (Ed.), John Wiley & Sons, Chapter 42.

Mathews, D.A., 1965: Some research on the lithium chloride radiosonde hygrometer and a guide for making it. Humidity and Moisture, Vol. 1, A. Wexler (Ed.), Reinhold, New York, 228-247.

Mcintutff, R.M., F.G. Finger, K.W. Johnson, and J.P. Laver, 1978: Day-night difference in radiosonde observations of the stratosphere and troposphere. NOAA Tech. Memo NWS NMC 63, 47pp.

Morrissey, J.F., and F.J. Brousaides, 1970: Temperature-induced errors in the ML-476 humidity data. J. Appl. Meteor., .8, 805-808.

National Oceanic and Atmospheric Administration, 1991a: Functional Precision of National Weather Service Upper-Air Measurements Using VIZ Manufacturing Co. "A" Radiosonde (Model 1492-510). NOAA Tech. Rep. NWS 44, Office of Systems Operations, Engineering Div., Test and Eval. Branch, Sterling, V A, 38 pp.

National Oceanic and Atmospheric Administration, 1991b: Functional Precision of National Weather Service Upper-Air Measurements Using VIZ Manufacturing Co. "B" Radiosonde (Model 1492-520). NOAA Tech. Rl'l?. NWS 45, Office of Systems Operations, Engineering Div., Test and Eval. Branch, Sterling, V A, 38 pp.

National Oceanic and Atmospheric Administration, 1991c: Functional Precision of National Weather Service Upper-Air Measurements Using Space Data Division Radiosonde (Model909-10- 01). NOAA Tech. Rep. NWS 46, Off. of Systems Operations, Engineering Div., Test and Eval. Branch, Sterling, VA, 41 pp. ·

Nordahl, L.S., 1982: Response. Bull. Amer. Meteor. Soc., 63, 1394.

Potts, L.W., 1980: Humidity sensor transfer equation. VIZ Radiosonde Bulletin. Tech. Pub. 80415A, VIZ Manufacturing Co., Philadelphia, PA 19144, 2 pp.

Potts, L.W., 1983: VIZ fast response humidity sensor equations. VIZ Radiosonde Bulletin. Tech. Pub. 880801, VIZ Manufacturing Co., Philadelphia, PA 19144, 2 pp. ·

88 Pratt, R.W., 1985: Review of radiosonde humidity and temperature errors. J. Atmos. Ocean. Tech., 2, 404-407.

Richner, H., and P.D. Phillips, 1981: Reproducibility of VIZ radiosonde data and some sources of error. J. Appl. Meteor., 20, 954-962.

Ruprecht, E., 1975: Diurnal temperature corrections for rawinsonde humidity sensors. Mon. Wea. Rev., 103: 352-355.

Schwartz, B. E., 1990: Regarding the automation of rawinsonde observations. Weather Forecasting, ~' 167-171.

Showalter, A.K., 1965: State-of-the-art survey on the application of hygrometry to meteorology, Humidity and Moisture, Vol. 2, Wexler, A. (Eel.), Reinhold, New York, 441-445.

Teweles, S., 1970: A spurious diurnal variation in radiosonde humidity records. Bull. Amer. Meteor. Soc., 51, 836-840.

U.S. Dept. of Commerce, 1993: Federal Meteorological Handbook No. 3: Rawinsonde Observations. Office of the Federal Coordinator for Meteorological Services and Supporting Research, Washington, DC, in press.

U.S. Weather Bureau, 1962: United States Radiosonde Compatibility Corrections for Application at Very High Levels and Instruments Schedule by Stations during 1959-60, Stratospheric Meteorology Research Project, Washington.

U.S. Weather Bureau, 1964: History and catalogue of upper air data for the period 1946-1960. Key to Meteorological Records Documentation No. 5.21, U.S. Department of Commerce, Washington, D.C., 352 pp.

Wade, C.G., and S.L. Bames, 1988: Geopotential height errors in NWS rawinsonde data at Denver. Bull. Amer. Meteor. Soc., 69, 1455-1459.

Wade, C.G., and D.E. Wolfe, 1989: Performance of the VIZ carbon hygristor in a dry environment. 12th Conf. on Weather Analysiys and Forecasting, Oct. 2-6, 1989, Monterey, CA, American Meteorological Society, Boston, MA, 58-62.

Williams, S.L., and D. T. Acheson, 1976: Thermal time constants of U.S. radiosonde sensors used . in GATE. NOAA Tech. Memo. EDS CEDDA-7, 16 pp.

VI. NATIONAL EXPERT

Joscph Facundo; US Department of Commerce; National Oceanic and Atmospheric Administration; National Weather Service; Silver Spring, MD 20910, USA. Information on overseas stations supported by the National Weather Service was provided by Jack Falkenhof.

89 VII. MISCELLANEOUS INFORMATION

NWS provides support and instruments to radiosonde stations outside the United States. These have always been supplied with VIZ radiosondes. The stations are: Bahamas, Barbados, Belize, Curacao, Grand Cayman, Jamaica, San Andres, Santo Domingo, Trinidad, and St. Maarten, all in the Caribbean. Of these, Barbados, Belize and Grand Cayman use the ART ground systems; all the others use GMD tracking systems.

Under the WMO Voluntary Cooperative Program, the United States also provides VIZ radiosondes to Bogota, Cape Verde, Costa Rica, Honduras, Paraguay, Bolivia, Peru, and Mexico (Guadalajara and Manzanillo). These stations use GMD tracking systems. Through 1991, the following stations in Mexico were also supported: Chihuahua, Empalme, Guadaloupe Island, Mazatlan, Merida, Mexico City, Monterrey, Socorro Island, and Veracruz.

90 VIET NAM, SOCIALIST REPUBLIC OF

I. CURRENT INSTRUMENTS AND PRACTICES (As of 12 January 1991)

MARS-2-2, MRZ-3A and A-22-IV radiosondes are used at stations 48820, 48855, and 48900, respectively. Radiosondes are precalibrated. Observations are made at 0000 and 1200 UTC at station 48820 and once daily at 0000 UTC at the other two. Solar radiation corrections are applied.

II. PAST CHANGES IN INSTRUMENTS AND PRACTICES

Since 1957, seven radiosonde types have been used: RZ-049, A-22-m, A22-IV, RKZ-5, MARS-2- 2, MRZ-3A, and VIZ. See microfiche Appendix 4 for station-specific information. 1 July 1984: Eliminated 1200 UTC observations at stations 48855 and 48900.

Ill. PLANNED CHANGES IN INSTRUMENTS AND PRACTICES

A-22-IV will be replaced in early 1992. Possible cessation of observations at stations 48855 and 48900 in 1991.

IV. STATION HISTORIES

See microfiche Appendix 4.

V. PUBLICATIONS

VI. NATIONAL EXPERT

Hoang The Xuong; Hydrometeorological Service of the Socialist Republic of Viet Nam; 4 Dang Thai Than Street; Hanoi; Viet Nam; TEL: 53467

91 4. DEWPOINT ALGORITIIl\1 CO:MPARISON

Even if all radiosonde stations launched the same type of radiosondes with the same sensors, there is the possibility of inhomogeneities in the reported data due to differences in the manner in which the measured data are converted to meteorological reports. One example is the conversion of the measured temperature (T) and relative humidity (U) data to dewpoint depression (D) for transmission. This section presents and compares the current and past methods used internationally to petform the conversion, as reported in survey responses.

The survey yielded information on 26 methods for obtaining D from T and U, and these are summarized in Table 2. Seventeen of these are different computational algorithms from 14 nations that are or were in use. These algorithms generally replaced manual techniques, including tabular and graphical methods, nomograms, and circular slide rules, also noted in Table 2. Many of the algorithms are based on the venerable Magnus equation for vapor pressure (Tetens, 1930), but the constants vary slightly from algorithm to algorithm. Others are based on more recent formulations of the saturation vapor pressure dependence on temperature (Buck, 1981; Hooper, 1986), and others (e.g., the one used in the United States) are complicated polynomial forms that cannot be traced in the literature.

It should be noted that about half the algorithms reported (and available to the reader in the microfiche Appendix 4) contained typographic or algebraic errors, such as misplaced parentheses or transposed numerals in constants. Although many of these errors were easily detected, others were subtle and gave plausible (although incorrect) results. Preliminary results of this comparison (Gaffen, 1992) overestimated the differences among some algorithms because of these subtle errors.

Each technique was evaluated over the meteorological range of temperature (-50 to 50°C, in 10°C increments) and relative humidity (10 to 100%, in 10% increments) to determine whether this wide variety of techniques introduces bias into the global data archive. For easy comparison, D computed from each technique was compared with D computed with an algorithm supplied by Prof. Dr. Dietrich Sonntag (Sonntag Algorithm in Table 2), based on his reformulation of the expressions for the dependence of saturation vapor pressure on temperature, using the .. International Temperature Scale 1990 11 (Sonntag, 1990). Use of this algorithm in this report is not meant to suggest it as a standard, although there is not, to my knowledge, any WMO recommended method for converting T and U to D. The current Swiss algorithm (Switzerland Algorithm 2 in Table 2) was proposed by the International Organizing Committee for the WMO Hygrometerlntercomparison (WMO, 1986); however, it is not an officially recommended formula.

Results of dewpoint depression computations and determinations for all methods are shown in Tables 3, 4, and 5 for temperatures of -20, 0, and 20°C, respectively. The results of Sonntag's (1990) algorithm, and the difference between that algorithm and each other method, are presented.

For transmission over the Global Telecommunications System, dewpoint depression is rounded to tenths of a degree forD < 5°C and to whole degrees at higher D values. Thus if two algorithms agree to this precision, they can be considered operationally compatible. On this basis, the methods are not in agreement with the Sonntag algorithm or with each other. However, none of the algorithms gives D different from the D derived from Sonntag' s algorithm by more than

92 0.1 oc forD < 5.0°C, or more than 1.0°C forD > 5.0°C. The manual methods sometimes show differences of 0.2 or 0.3°C forD < 5.0°C. However, the values given for the manual methods are often based on interpolation, which is subject to human error. Therefore, these values should not be considered as accurate as those derived from numerical algorithms.

Probably the most important difference among the methods involves the establishment of cutoff temperature, pressure, or humidity values. Nine techniques involve a temperature cutoff below which no humidity data are reported; however, the cutoff ranges from -40°C to -65°C. The relative humidity cutoffs range from 10 to 20% , and different methods handle values below the cutoff differently. This inhomogeneity in humidity reporting practices will influence upper tropospheric and stratospheric data, and data from polar regions, most severely.

If one wished to eliminate the differential effect of the algorithms, one might use them to recover from a (T,D) report the U that must have been measured. This method was used to quantify the bias in the global data archive that can be attributed to these algorithms. Pairs ofT and D were used to recover U for the temperature range -40 to 50°C, in 5°C increments. Values of D ranged from 0.1 to 5. 0 o C in 0.1 o C increments, then from 5 to 40 o C in 1 o C increments (which is consistent with the precision of the D reports in archived radiosonde data). Thus 85 trials were made for each T value. Each trial involved using a fixed T value and a first -guess U value to computeD, and iterating with new U values until the computed D was within 0.01 oc of the desired D value. After thus obtaining U from all 16 algorithms, the resulting range (R) was computed as the difference between the maximum and minimum U values.

Figure 1 shows that for T between 0 and 30°.C, R never exceeds 1%, and the algorithms are in very good agreement. Below 0°C, R increases, and forT < -20°C, R exceeds 1% for more than 75% of the (T ,D) pairs. At the lowest temperatures, R can even exceed 3%. The agreement also deteriorates at T > 30°C. The explanation is probably that the saturation vapor pressure formulations are generally forced to fit exactly at the freezing point and are fits to data that are most reliable above freezing. Nevertheless, for most (T,D) pairs, the range of the· computed U values is considerably less than 3%. Random errors in radiosonde U measurements (Nash and Schmidlin, 1987), and most systematic differences in U measurements from different contemporary radiosondes (lvanov et al., 1991) are in the several percent range, so the effect of the algorithms is generally smaller.

In summary the differences in dewpoint depression methods are a source of inhomogeneity in archived upper-air data. The same temperature and relative humidity observations at two stations using different algorithms could result in different dewpoint depressions being computed, but the difference is generally only a single tenth or whole degree, depending on the dewpoint depression. The problem is most noticeable at the extremes of the meteorological temperature range. The overall effect of the different methods is small compared with other sources of error in radiosonde humidity data, with the exception that the use of different cutoff values introduces a large source of inhomogeneity in cold, dry environments.

93 Table 2. Summary of dewpoint depression algorithms and methods used. Symbols are T, temperature (K); t, temperature = T - 273.15 (°C); Td, dewpoint (K); td, dewpoint (°C); D, dewpoint depression = T- Td = t- ~; U, relative humidity(%); u, relative humidity = U/100; p, pressure (hPa); In, natural logarithm; log, base-10 logarithm.

Method, alphabetically by country, reference, and dates used, when available.

Belgium Algorithm 1 (Used 1972-1989) For

t > -40°C

(log u + 5.07026 1 1 log~) - =-- 2954.98

Solve iteratively. Belgium Algorithm 2 (Used since 1990.) For

T = 2 Tc d 2c-Tlnu

c = 2771.5 - 15 1n u - 2 t

Bulgaria Algorithm

t = 237.3 (7.5 t + X) d 1779.75 -X

X = 0.43429 (237.3 +. t) 1n u

Canada Algorithm For

t > -65°C

D = T - ____.:..T __ _ _ 461.51 T 1n u 1 Ly(7)

L,(I') is from WMO-No.188.TP.94 (1966) Table 4.5.

94 China Algorithm For

and

p > 10 hPa

D=t-!!. b

7 5 a = 237.3 [ · t + log u - 2] 237.3 + t

75 b = 7.5 - [ t + log U - 2] 237.3 + t

Cuba Algorithm (Used since 1989) For

and u::!: 15%

a=t+236

b = 0.4343 (2 - In U)

b < 0.005 then set

b = 0.05

D =----=a~- 1762 b + 1 a

95 Czechoslovakia Algorithm (Used 1980-1989; since 1990, humidity not reported above 300 hPa) For

t ~ -40"C if u < 10% then set u = 10%

D = t _ 237.3 lo~ a 7.5 - log a

7.5 t a= u 10~

Czechoslovakia Graph (Hesse, 1961; used until 1979; interpolate from a family of curves of constant Ton a plot of U vs. D) Denmark Nomogram (T-T/TIU diagram AENG 1967; used until late 1970's; interpolate from a family of curves of constantD on a plot of U vs. 1) Finland Algorithm

235 log a D = t- 1.45 -log a

7.5 t a = u 10237.3 •,

Germany Algorithm 1 (Used in former Federal Republic of Germany)

D = t - c3 In (u X)

c2 - In (u X)

c t X= exp-2 c3 + t

Numerical values of coefficients were not provided.

96 Germany Algorithm 2 (Used in former German Democratic Republic)

D = t _ 235 ~og u + X) 7.45 - log u - X

X = 7.45 t 235 + t

India Algorithm (Fan and Whiting, 1987) For

and

u :2: 15-%

66_1_.1_3_-_2_3_7._3 _lo_,.g"'"(E)~ td = - log(E) - 10.286

r1om T - 2148.!109] E = u loL T - 35.85

New Zealand Table (Data correspond to WMO Table 4.21.1; relative humidity as a function of temperature and thermodynamic dewpoint temperature) New Zealand Nomogram (Diagrams titled 3.4 Dew Point Depression, 2-17-15 and 2-17-16, October 1988; data correspond to WMO Table 4.21.; D is given as a function ofT and U) New Zealand Slide Rule (Mixing ratio calculator, U.S. Navy ML-326/UM; results provided by Mr. Ralph Pannett) Poland Algorithm For

235.0 (*+a) D = t- lnu 7.4895- -- -a In 10

7.45 t a= 235 + t

Switzerland Algorithm 1 (Used 1959(?)-March 1990)

t = 5390 (t + 273.16) - 273.16 d 5390 - (t + 273.16) In u

97 Switzerland Algorithm 2 (WMO, 1986; used since April1990)

t = b(b + t)ln u + a t d ab - (b + t)ln u

where

a = 17.502

b = 240.97

U.K. Algorithm (Hooper, 1986)

3 Td = -159.2 + 152.5 z- 31.34 z2 + 15.37 z

1 6 Z = [(1.3521 + 1.6369x10-2T + 3.1794x10-5:r2 - 1.4892xlo-7T3) u]l2

U.K. Slide Rule (RadioSonde Dew Point Depression Calculator MK 1, Meteorological Office, Met. Ref. 29760; single circular device with a concentric circular wheel that exposes only one set of values of D at a given U for t > -40°C) U.S.S.R. Algorithm (Zaitseva, 1990)

T = 237.3 [7.5 t + (237.3 + t) log u] d 237.3 x 7.5 - (237.3 + t) log u

U.S.S.R. Graph Scale (Insert sheet number 24 from Central Aerological Observatory publication, 1973; displacement of the observed t from a reference value is measured on a scale; that displacement is used to determine D at a given U using a second scale; used with manual systems)

98 U.S. Algorithm. For

t s; -40·c

D is missing. Otherwise, if u < 20%

D = 30

Otherwise, if

u ~ 20%

3 D = a1 (1 - u) + [~ (1 - u)] + ~ (1 - u)14

a1 = 14.55 + 0.114 t

~ = 2.5 + 0.007 t

a3 = 15.9 + 0.117 t

U.S. National Weather Service Slide Rule (National Weather Service Psychrometric Calculator, TELEX Communications, 1974; Model FCW-13A-1; concentric circular scales; set U=100% opposite T, and read Td at the setting of the measured U) U.S. Air Force Slide Rule (Air Force Psychrometric Calculator, Felsenthal Instruments Co., ML-429/UM); Concentric circular scales; concentric circular scales; set U=lOO% opposite T, and read Td at the setting of the measured U)

99 Sonntag (1990; presented for comparison only, not used in any country) For

Td = 4.0413x1o-s + 13.715 x + 0.84262 x2 + 1.9048x10-2 x3 + 7.8158x10-3 x4 and for

Td = 3.63717x1o-s + 13.7204 x + 0.736631 x2 - ·3.32136xlo-2 x3 + 7.78591xlO'"" x4 where

ew(t) u] X -In [ 6.11213

ln(ew> = -6096.9385C1 + 16.635794 - 2.711193x1o-2 t + 1.673952xlo-5t 2 + 2.433502 ln(t)

100 Table 3. Results of dewpoint depression algorithms and methods. The table gives the dewpoint depression (°C) results of the Sonntag (1990) algorithm at -20°C, and at 10% increments of relative humidity. Then the difference (°C) between the Sonntag algorithm and each of the dewpoint depression methods follow (Sonntag algorithm minus national method). If the method is not valid for a given temperature-relative humidity pair, a double dash (--) appears in the table. If a method would not be used for a given pair due to cutoffs, an asterisk (*) follows the value.

Relative Humidity (%) 10 20 30 40 50 60 70 80 90

Sonntag Algorithm 23.96 17.29 13.18 10.17 7.78 5.78 4.07 2.56 1.21

Belgium Algorithm 1 -0.03 -0.02 -0.02 -0.01 -0.01 -0.00 -0.00 0.00 0.00 Belgium Algorithm 2 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.01 0.01 Bulgaria Algorithm -0.31 -0.20 -0.14 -0.10 -0.07 -0.05 -0.03 -0.02 -0.01 Canada Algorithm 0.21 0.10 0.05 0.03 0.02 0.01 0.00 0.00 0.00 China Algorithm -0.31 -0.20 -0.14 -0.10 -0.07 -0.05 -0.03 -0.02 -0.01 Cuba Algorithm -0.37* -0.24 -0.17 -0.13 -0.09 -0.06 -0.04 -0.02 -0.01 Czechoslovakia Alg. -0.31 -0.20 -0.14 -0.10 -0.07 -0.05 -0.03 -0.02 -0.01 Czechoslovakia Graph 0.04 -0.29 -0.18 -0.17 -0.08 0.22 0.03 0.14 0.29 Denmark Nomogram -0.06 0.01 0.02 0.03 0.02 0.02 -0.07 -0.06 -0.01 Finland Algorithm -0.50 -0.35 -0.27 -0.22 -0.18 -0.15 -0.12 -0.10 -0.08 Germany Algorithm 2 -0.44 -0.29 -0.21 -0.15 -0.11 -0.08 -0.05 -0.03 -0.01 India Algorithm -0.27* -0.16 -0.10 -0.06 -0.03 -0.00 0.02 0.03 0.05 New Zealand Table -0.06 -0.09 0.02 0.03 0.02 0.02 0.03 0.04 -0.01 New Zealand Nomogram 0.34 0.41 0.52 0.53 0.52 0.52 0.03 0.04 -0.01 New Zealand Sl. Rule -0.09 0.02 0.03 -0.08 -0.08 0.03 -0.06 -0.01 Poland Algorithm -0.55 -0.37 -0.27 -0.21 -0.15 -0.11 -0.07 -0.04 -0.02 Switzerland Alg. 1 0.75 0.50 0.37 0.27 0.20 0.15 0.10 0.07 0.03 Switzerland Alg. 2 -0.17 -0.10 -0.07 -0.05 -0.03 -0.02 -0.01 -0.01 0.00 U.K. Algorithm -0.01 0.01 0.03 0.04 0.05 0.05 0.06 0.06 0.07 U.K. Slide Rule 0.04 -0.29 -0.18 -0.17 0.22 0.22 0.03 0.04 -0.01 U.S.S.R. Algorithm -0.31 -0.20 -0.14 -0.10 -0.07 -0.05 -0.03 -0.02 -0.01 U.S.S.R. Graph Scale 0.04 -0.29 -0.18 -0.17 0.22 0.22 0.13 0.04 -0.01 U.S. Algorithm -0.23* -0.15 0.01 0.04 0.00 -0.03 -0.03 0.00 0.03 U.S. NWS Slide Rule -0.07* -0.07 -0.07 -0.06 -0.06 -0.00 -0.01 -0.00 -0.05 U.S. A.F. Slide Rule -0.07* -0.12 -0.13 -0.06 -0.06 -0.00 -0.01 -0.00 0.01

101 Table 4. Same as Table 3, but for 0°C.

Relative Humidity (%) 10 20 30 40 50 60 70 80 90

Sonntag Algorithm 28.07 20.31 15.51 11.98 9.17 6.82 4.80 3.03 1.44

Belgium Algorithm 1 -0.01 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.00 Belgium Algorithm 2 -0.00 0.01 0.02 0.01 0.02 0.01 0.01 0.01 0.00 Bulgaria Algorithm -0.15 -0.08 -0.04 -0.02 -0.01 -0.00 0.00 0.00 0.00 Canada Algorithm 0.34 0.19 0.12 0.08 0.05 0.04 0.02 0.01 0.01 China Algorithm -0.15 -0.08 -0.04 -0.02 -0.01 -0.00 0.00 0.00 0.00 Cuba Algorithm -0.19* -0.10 -0.06 -0.04 -0.02 -0.01 -0.01 -0.00 0.00 Czechoslovakia Alg. -0.15 -0.08 -0.04 -0.02 -0.01 -0.00 0.00 0.00 0.00 Czechoslovakia Graph -0.07 -0.31 -0.01 0.02 0.03 0.18 0.10 0.17 0.36 Denmark Nomogram -0.07 -0.11 -0.01 0.02 0.03 -0.02 -0.00 -0.03 -0.04 Finland Algorithm -0.26 -0.15 -0.10 -0.06 -0.04 -0.03 -0.01 -0.01 -0.00 Germany Algorithm 2 -0.26 -0.15 -0.10 -0.06 -0.04 -0.03 -0.01 -0.01 -0.00 India Algorithm -0.11* -0.03 0.01 0.03 0.04 0.05 0.05 0.06 0.06 New Zealand Table -0.07 -0.01 -0.01 0.02 0.03 -0.02 -0.00 -0.03 -0.04 New Zealand Nomogram 0.53 0.49 0.59 0.52 0.53 0.58 -0.00 -0.03 -0.04 New Zealand Sl. Rule -0.07 -0.11 -0.01 0.02 0.03 -0.02 -0.00 0.07 -0.04 Poland Algorithm -0.39 -0.25 -0.17 -0.12 -0.09 -0.06 -0.04 -0.02 -0.01 Switzerland Alg. 1 0.47 0.29 0.20 0.14 0.10 0.07 0.05 0.03 0.01 Switzerland Alg. 2 -0.05 -0.01 0.00 0.01 0.01 0.01 0.01 0.01 0.00 U.K. Algorithm 0.04 0.07 0.08 0.09 0.09 0.09 0.09 0.09 0.09 U.K. Slide Rule -0.07 -0.31 0.49 D.02 -0.17 0.18 -0.00 -0.03 -0.04 U.S.S.R. Algorithm -0.15 -0.08 -0.04 -0.02 -0.01 -0.00 0.00 0.00 0.00 U.S.S.R. Graph Scale -0.07 -0.31 0.49 0.02 -0.17 0.18 -0.00 0.17 -0.04 U.S. Algorithm 0.05* 0.03 0.14 0.14 0.06 0.00 -0.01 0.01 0.03 U.S. NWS Slide Rule 0.04* 0.03 -0.01 0.02 -0.06 0.01 -0.02 -0.03 0.01 U.S. A.F. Slide Rule 0.04* 0.19 0.16 0.19 0.06 0.12 0.03 0.09 0.01

Table 5. Same as Table 3, but for 20°C.

Relative Humidity (%) 10 20 30 40 50 60 70 80 .90

Sonntag Algorithm 32.53 23.62 18.09 14.00 10.74 8.00 5.64 3.56 1.69

Belgium Algorithm 1 0.02 0.02 0.01 0.00 -0.00 -0.00 -0.01 -0.00 -0.00 Belgium Algorithm 2 -0.02 -0.02 -0.04 -0.04 -0.03 -0.03 -0.02 -0.02 -0.01 Bulgaria Algorithm -0.03 -0.00 -0.01 -0.01 -0.01 -0.01 -0.00 -0.00 -0.00 Canada Algorithm 0.50 0.28 0.16 0.09 0.05 0.03 0.01 0.00 -0.00 China Algorithm -0.03 -0.00 -0.01 -0.01 -0.01 -0.01 -0.00 -0.00 -0.00 Cuba Algorithm -0.05* -0.02 -0.01 -0.01 -0.01 -0.01 -0.01 -0.01 -0.00 Czechoslovakia Alg. -0.03 -0.00 -0.01 -0.01 -0.01 -0.01 -0.00 -0.00 -0.00 Czechoslovakia Graph -0.03 -0.12 -0.09 -0.00 0.06 -0.00 0.06 0.14 0.31 Denmark Nomogram 0.07 0.08 -0.09 -0.00 0.06 -0.00 -0.04 -0.06 -0.09 Finland Algorithm -0.07 -0.01 0.00 0.01 0.02 0.03 0.03 0.04 0.04 Germany Algorithm 2 -0.11 -0.05 -0.04 -0.03 -0.03 -0.02 -0.01 -0.01 -0.01 India Algorithm 0.02* 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.06 New Zealand Table -0.03 -0.02 0.01 -0.00 -0.04 -0.00 -0.04 0.04 0.01 New Zealand Nomogram 0.47 0.58 0.51 0.50 0.56 0.50 0.56 0.04 0.01 New Zealand Sl. Rule -0.03 -0.02 0.01 -0.00 -0.04 -0.00 -0.04 -0.06 0.01 Poland Algorithm -0.26 -0.17 -0.13 -0.10 -0.08 -0.06 -0.04 -0.03 -0.01 Switzerland Alg. 1 0.10 -0.02 -0.07 -0.09 -0.09 -0.08 -0.06 -0.04 -0.02 Switzerland Alg. 2 0.02 0.02 0.01 -0.00 -0.00 -0.01 -0.01 -0.00 -0.00 U.K. Algorithm 0.09 0.09 0.08 0.08 0.08 0.08 0.08 0.08 0.08 U.K. Slide Rule 0.47 0.38 -0.09 -0.00 0.26 -0.00 0.36 0.04 0.01 U.S.S.R. Algorithm -0.03 -0.00 -0.01 -0.01 -0.01 -0.01 -0.00 -0.00 -0.00 U.S.S.R. Graph Scale 0.47 0.38 -0.09 -0.00 0.26 -0.00 0.36 0.04 -0.09 u.s. Algorithm 0.21* 0.07 0.13 0.08 -0.02 -0.09 -0.09 -0.05 0.01 U.S. NWS Slide Rule 0.03* 0.05 0.08 0.11 0.04 0.05 0.03 0.05 0.03 U.S. A.F. Slide Rule -0.08* -0.06 -0.09 -0.17 -0.18 -0.06 -0.08 -0.06 -0.03

102 100~------~ &..&.&.&&. Ro nge exceeds 1% ••••• Range exceeds 3%

-(f) 0 L 1-

0 60 -+-' 0 1-

4- 0

(]) 01 40 0 -+-' c (])... u L (]) Q_ 20

o~--~~~--~~~~--~~----~~~--~~~--~--~ -50 -40 -30 -20 -10 0 10 20 30 40 50 60 Temperature (deg. C)

Figure 1. The percentage of trials, as a function of temperature, for which the range of back calculated relative humidity exceeds 1 and 3 %. The range is over 16 algorithms for dewpoint depression. Each trial is for a different value of dewpoint depression, and for each temperature, 85 trials were made.

103 5. CONCLUSIONS

As a result of a survey of WMO Members conducted in 1990, historical changes in radiosonde instruments and practices have been documented for 48 nations. The focus of the survey and of the responses was national changes affecting temperature and humidity measurements, although some information on station histories and wind and pressure measurements was also collected. Summaries for each nation include information on instrument changes and changes in observing and data-reporting practices. Bibliographic information has also been gathered.

A comparison of 26 techniques used to convert measured relative humidity and temperature to dewpoint depression shows the heterogeneity in the global data due simply to this post measurement treatment of the data. The different techniques introduce a bias in the data that is, in general, smaller than typical measurement errors or differences in measurements among contemporary instruments. However, an impo'rtant inhomogeneity results from the use of temperature, humidity, and pressure cutoffs in the methods, which affect the data from cold, dry regions most severely.

This survey was conducted to facilitate the interpretation of global radiosonde data archives by climate researchers. It is hoped that the information collected will allow easier identification of changes in upper-air temperature and humidity data that are related to changes in instruments or observing practices and, possibly, adjustment of historical data to account for changes in biases in the record.

Many unanswered questions remain, however, related to historical changes in radiosonde instruments and practices. Wind measurements were not treated by this study, and little focus was placed on changes in pressure sensors. Much more could be learned about the specifics of radiation corrections applied to temperature data. Although station histories were provided by some nations and are available from some others, not all countries have assembled such information and no attempt was made here to put the available station history information in a compatible format. Finally, of course, not all countries operating upper-air stations responded to the survey, so gaps remain in our knowledge of the history of the global upper-air observing program.

Because of the difficulty of reconstructing upper-air data histories ex post facto, and because such histories will continue to be useful, indeed necessary, in future decades, WMO Members are encouraged to maintain accurate and complete records of changes in instruments and practices as well as station histories. The WMO can facilitate international collection and exchange of such information. However, it remains the responsibility of individual Members to record the information initially, since they are best able to do so in a thorough and precise manner.

104 6. BffiLIOGRAPHIES

The following bibliographies give general references in different subject areas. References dealing with specific national radiosonde networks are given in the appropriate national summaries in Section 3. 2.

6.1. Bibliography on Dewpoint Depression Computations

Buck, A.L., 1981: New equations for computing vapor pressure and enhancement factor. J. Appl. Meteor., 20, 1527-1532.

Central Aerological Observatory, 1973: Handbook for Hydrometeorological Stations and Posts. Issue 4. Upper-air Observations: Part ffia. The Temperature and Wind Radiosounding by the Meteorit-RKZ. Gydrometeoizdat, Leningrad, 256 pp.

Fan, J., and J. Whiting, 1987: Calculation and accuracy of humidity value (sic). Sixth Symposium on Meteorological Observations and Instrumentation, American Meteorological Society, Boston, 237-240.

Elliott, W.P., and D.J. Gaffen, 1993: Effects of conversion algorithms on reported upper-air dewpoint depression, Bull. Amer. Meteor. Soc., in press.

Gaffen D.J., 1992: Preliminary results of the CIMO survey on historical changes in radiosonde instruments and practices. WMO Technical Conference on Instruments and Methods of Observation (TEC0-92), Vienna, Austria, 11-15 May 1992, WMO/TD-No. 462 Instruments and Observing Methods Report No. 49, World Meteorological Organization, Geneva, 426-430.

Garand, L., C. Grassotti, J. Halle, G.L. Klein, 1992: On differences in radiosonde humidity reporting practices and their implications for numerical weather prediction and remote sensing, Bull. Amer. Meteor. Soc., 73, 1417-1423.

Hesse, W., 1961: Handbuch der Aerologie. Akademische Verlagsgesellschaft Geest and Portig K.G., Leipzig, 897 pp.

Hooper, A.H., 1986: Algorithms for Automatic Aerological Soundings. WMO/TD-No. 175. Instruments and Observing Methods Report No. 21, World Meteorological Organization, Geneva, 50 pp.

Sonntag, D., 1989: WMO Assmann aspiration psychrometer intercomparison (Potsdam, GDR, 1987), Final Report. WMO/TD-No. 289. Instruments and Observing Methods Report No. 34, World Meteorological Organization, Geneva, 177 pp.

Sonntag, D., 1990: Important new values of the physical constants of 1986, vapor pressure formulations based on the ITS-90, and psychrometric formulae. Z. Meteor., 70, 340-344.

Tetens, 0., 1930: Ueber einige meteorologische Begriffe. Z. Geophys., ~' 297-309.

105 World Meteorological Organization, 1986: WMO Instruments and Methods of Observation Programme. International Organizing Committee for the WMO Hygrometer Intercomparison, First Session, Oslo, 12-16 May 1986, Final Report, World Meteorological Organization, Geneva.

Zaitseva, N., 1990: Aerologica, Gidrometeoizdat, Leningrad, 325 pp. (In Russian and in English translation.)

6.2. Bibliography on Radiosonde Performance and Comparisons

Author unknown, 1966: Comparaison de radiosondages par jumelage. Ciel Terre, 82, 332-339.

Annema, K.H., W.A.A. Monna, and S.H. Muller, 1984: A comparative investigation of three commercial rasiosonde systems. Memorandum 84-8, Royal Netherlands Meteorological I.nstitute (KNMI), De Bilt.

Badgley, F .1., 1957: Response of radiosonde thermistors. Response of radiosonde thermistors, Rev. Sci., 28, 1079-1084.

Ballard, H., and R. Rubio, 1968: Correction to observed rocketsonde and balloon-sonde temperatures. J. Appl. Meteor., 1, 919-928.

Bosart, L.F., 1990: Degradation of the North American radiosonde network. Weather Forecasting, 2, 527-528.

Finger, F. G., and F.J. Schmidlin, 1991: Upper air measurements and instrumentation workshop. Bull. Amer. Meteor. Soc., 72, 50-55.

Forrester, G.F., 1985: A summary of the quality of radiosonde geopotential measurements. U.K. Meteorological Office, Obs. Serv. Memo. OSM No. 33.

Goltsova, K.l., O.V. Marfenko, M.A. Petrosyants, and V.D. Reshetov, 1974: Intercomparison of the Soviet and the American systems for ship radiosounding. Meteor. Gidrol., 12, 92-97.

Hawson, C.L., 1970: Performance requirements of aerological soundings: An assessment based on atmospheric variability. Technical Note No. 112, WM0-No.267.T.P.151, World Meteorological Organization, Geneva, 47 pp.

Hooper, A.H., 1975: Studies on radiosonde performance, vol. I. Upper-Air Sounding Studies, w;MO Tech. Note 140. WMO-No. 394, World Meteorological Organization, Geneva, 109 pp.

Hooper, A.H., 1986: WMO international radiosonde comparison, Phase I, Beaufort Park, U.K., 1984, WMO/TD-No. 174, World Meteorological Organization, Geneva, 118 pp.

Ivanov, A., A. Kats, S. Kurnosenko, J. Nash, and N. Zaitseva, 1991: WMO international radiosonde intercomparison phase m (Dzhambul, USSR, 1989) fmal report. WMO/TD-No. 451,

106 Instruments and Observing Methods Rt:mort No. 40, World Meteorological Organization, Geneva, 135 pp.

Karhunen, P., G.P. Trifonov, and V.A. Yarmonov, 1987: The intercomparison of the Soviet radiosonde system "Meteorit-2-MARS-2-0KA-3" with the Finnish system MicroCORA. Meteor. Gidrol. , 11.

Kitchen, M., 1989: Compatibility of radiosonde geopotential measurements. WMO Instruments and Observing Methods Rt:mort No. 36, World Meteorological Organization, Geneva.

Kuzenkov, A.F., and V.I. Shlyakov, 1976: The realization of a programme of international radiosondes comparisons. Tr. CAO, 118, 33-39.

Lugeon, J., and P. Ackermann, 1955: Homog6n6it6 du reseau europ6en de radiosondages. Note Technique No. 14, WMO-No.51.TP.20, World Meteorological Organization, Geneva, 11 pp.

Lugeon, J., and P. Ackermann, 1955: Les anomalies du reseau aerologique europ6en. Annales de la Station Centrale Suisse de M6t6orologie.

Malet, L.M., 1954: Diverses experiences de comparaison de radiosondes, Note Technique No. 5, WMO-No.35.TP.11, World Meteorological Organization, Geneva, 11 pp.

Monna, W.A.A., amd K.H. Annema, 1988: A comparative investigation of the VaisaHi. MicroCORA and DigiCORA ground systems. (Contribution to WMO Technical Conference on Instruments and Methods of Observation, TEC0-1988, Leipzig, May 1988), Memorandum FM-88- ~, World Meteorological Organization, Geneva.

Nash, J., 1985: Assessment of efficiency of modern radiosonde measurements. WMO Rt:mort No. 23, World Meteorological Organization, Geneva.

Nash, J. and F.J. Schmidlin, 1987: WMO international radiosonde intercomparison (U.K., 1984, U.S.A., 1985) fmal report. WMO/TD-No. 195, Instruments and Observing Methods Report No. 30, World Meteorological Organization, Geneva, 103 pp.

Organisation M6t6orologique International (OMI), 1951: Comparaison mondiale des radiosondes, Payeme, mai 1950, Acte fmal: Vol. I, Destine aux aerologistes; Vol. IT, Destine aux m6t6orologistes synopticiens. Payerne et Zurich .

. Organisation M6t6orologique International (OMI), 1952: Comparaison mondiale des radiosondes, Payeme, mai 1950, Act fmal: Vol. m, Rapports nationaux, conclusions. Zurich.

Organisation M6t6orologique Mondiale, 1956: Rapport fmale du groupe de travail pour la comparaison mondiale des radiosondes. Payerne et Zurich.

Painter, H.E., 1950: International radiosonde trials. Weather, V, 307-310.

107 Parker, D.E., 1982: An intercomparison of Russian and Japanese upper-air data, Meteor. 013 Branch Memo. No 97, U.K. Meteorological Office.

Phillips, P.D., H. Richner, J. Joss, and A. Ohmura, 1981: ASOND-78: An intercomparison of Vaisala, VIZ and Swiss radiosondes. Pure Appl. Ge()phys., 119, 259-277.

Reiker, J. 1976: Comparaison de donnees de radiosondages effectues en avril1976 aPayeme avec les systemes suisse "BASORA" et fmlandais "CORA". Rapport de travail No. 66 de l'Institut Suisse de Meteorologie, 10 pp.

Richner, H., and P.D. Phillips, 1982: The radiosonde intercomparison SONEX Spring 1981, Payeme. Pure Appl. Geophys., 120, 851-1198.

Schmidlin, F.J., R.O. Olsen, and J. Facundo, 1989: Results of a comparison of radiosondes used by United States agencies. Fourth WMO Technical Conference on Instruments and Methods of Observation, Instruments and Observing Methods Report No. 35, WMO/TD-No 303, World Meteorological Organization, Geneva, 65-70.

Schwartz, B. E., and C.A. Doswell m, 1991: North American rawinsonde observations: Problems, concerns, and a call to action. Bull. Amer. Meteor. Soc., 72, 1885-1896.

Shlyakhov, V.I., and N. Arizume, 1968: On the USSR/Japanese reference radiosonde comparison at Tateno on Dec. 14-20, 1968. CIMO Working Group on Radiosonde and Radiowind Measurements, World Meteorological Organization, Geneva, 30 pp.

Shlyakhov, V.I., and A.F. Kuzenkov, 1973: The results of international comparison of the reference radiosondes. Meteor. Gidrol., 1, 94-98.

Talbot, J.E., 1972: Radiation influences on a white-coated thermistor temperature sensor in a radiosonde. Australian Meteor. Mag., 20, 222-233.

Uddstrom, M.J., 1989: A comparison ofPhilips RS4 and Vaisrua RS80 radiosonde data. J. Atmos. Oceanic Tech., .6(1).

World Meteorological Organization, 1978: The compatibility of upper-air data: Part I, Research on compatibility of data from radiosondes, rocketsondes and satellites, by F.G. Finger and R.M. Mcinturff; Part ll, The compatibility and performance of radiosonde measurements of geopotential height in the lower stratosphere for 1975-76, by E.A. Spackman. WMO-No. 512, Technical Note No. 163, Geneva, 103 pp.

Zaitseva, N.A., 1976: On the radiosonde intercomparison in the GATE experiment. Proceedings of Atlantic Tropical Experiment of 1974: Vol. I- Atmosphera. Gidrometeoizdat, Leningrad, 712- 721.

Zaitseva, N.A., R.K. Ahmetyanov, and P. Karhunen, 1989: On the results of the intercomparison between the Soviet and Finnish radiosondes. Meteor. Gidrol., 1~ 105-110.

108 6.3. Bibliography on the Use of Radiosonde Data for Climate Research

Cox, D.I., and D.E. Parker, 1992: The effects of changes in radiosonde equipment on upper-air "Climat" data, Discussion Paper (E Division), Hadley Centre, Meteorological Office, Bracknell, U.K., 75 pp.

Elliott, W.P., and D.J. Gaffen, 1991: On the utility of radiosonde humidity archives for climate studies, Bull. Amer. Meteor. Soc .. 72, 1507-1520.

Hutchings, J.W., 1961: Some effects of deficiencies in upper-level humidity records. J. Geophys. Res., 66, 131-134.

Parker, D.E., 1980: Climate change or analysts' artifice? An examination of grid-point upper-air height and thickness data from various sources. Meteor. Mag., 109, 129-152.

Peixoto, J.P., and A. H. Oort, 1992: Physics of Climate. American Institute of Physics, New York, 520 pp.

Thomas, H.A., 1938: The determination of the meteorological conditions of the atmosphere by the use of radio-sounding balloons. Proc. Roy. Soc. London. A, 167, 227.

6.4. Bibiography of Other Relevant References

Haw son, C.L., 1970: Performance requirements of aerological instruments. Tech. Note No. 112, WMO-No. 267. TP. 151, World Meteorological Organization, Geneva.

Hayashi, H., Y. Sekiguchi, and A. Yada, 1956: On solar radiation error and its correction of Japanese radiosonde. JMA Geophys. Mag., 27(3), 361-375.

Suzuki, S., and M. Asahi, 1978: Influence of solar radiation on the temperature measurement before and after the change of the length of suspension used for the Japanese radiosonde observation. J. Met. Soc. Japan, 56, 61-64.

World Meteorological Organization, 1981: Report of frrst sesson of the CIMO working group on upper air data compatibility, Geneva, 26-30 26-30 January 1981. Meeting Report No. 81-2, Commission for Instruments and Methods of Observation, Geneva, 24 pp.

World Meteorological Organization, 1981: WMO catalogue of radiosondes in use by members, 1981. Instruments and Observing Methods Report No. 5, Geneva, 12 pp.

World Meteorological Organization, 1982: WMO catalogue of radiosondes in use by members, 1982. Upper-air data compatibility, Instruments and Observing Methods Report No. 11, Geneva, 23 pp.

World Meteorological Organization, 1983: Guide to Meteorological Instruments and Methods of Observation, Fifth edition. WMO-No. 8, Geneva.

109 World Meteorological Orgatrization, 1986: WMO catalogue of radiosondes and upper-air wind systems in use by members. Instruments and Observing Methods Report No. 27, WMO/TD-No. 176, Geneva.

110 7. ACKNOWLEDGMENTS

This report would not have been possible without the efforts of many individuals. Recognizing the potential importance of instrument changes on climatological humidity data, Drs. W.P. Elliott and J.K. Angell of the National Oceanic and Atmospheric Adminstration (NOAA) Environmental Research Laboratories, Air Resources Laboratory, had the original idea of conducting a survey of radiosonde histories. Mr. H. April, of the NOAA, National Weather Service, International Mfairs Branch, facilitated initial coordination with WMO.

Mr. K. Schulze, of the WMO Secretariat, World Weather Watch Department, coordinated the surveys and the publication of the report. Drs. J. Miller, C. Bhumralkar and A. Moura and Mssrs. G. O'Brien and J. Buizer, all of NOAA, helped establish personal contact with some national experts. Mr. Y. Spolter, a summer intern at the Air Resources Laboratory, assisted in compiling the survey results and preparing the microfiche.

Mssrs. M. Friedman and T. Curran of VIZ Manufacturing Company, Mssrs. H. Hultin and J. Horhammer of Vaisala Oy, representatives of Dr. Graw Messgerate GmbH & Co., and Dr. N. Zaitseva of the Central Aerological Institute, Moscow, all provided detailed information on the nomenclature and characteristics of radiosondes manufactured by their organizations. Dr. D. Sonntag provided his most recent saturation vapor pressure and dewpoint depression formulae.

Helpful comments on the manuscript were provided by J.K. Angell, W.P. Elliott, R. Eskridge, K. Schulze, and F. Schmidlin. Ms. C. Sweet of the NOAA Environmental Research Laboratories edited the manuscript.

Most important, this report is based on the diligent work of the national experts who responded to the survey and that of unnamed scores of individuals whose past records of radiosonde historical information were the basis for the national responses.

Partial support for this work was provided by the NOAA National Climatic Data Center, Comprehensive Aerological Research Data Set program, managed by Dr. R. Eskridge.

111 Appendix 1. Preliminary questionnaire (WMO Reference No. W/10/QPC Annex).

QUESTIONNAIRE

1. Is your country interested in participating in a detailed survey of historical changes in radiosonde instruments and practices?

YES NO

2. Does your country have available records of changes in radiosonde instruments, observing practices, or methods of observation? YES NO

3. Apart from written records, might there be information on such changes which is known by national experts?

YES ____ NO

4. If you answered "YES" to Question 1, please provide the name of an individual who may be contacted to co-ordinate your Meteorological Service's responses to such a survey.

Member country:

Name of expert:

Address:

Telephone Number:

Telex No.: ..

Telefax No. :

112 Appendix 2. Detailed questionnaire (WMO Reference N~. W/10/QPC Annex 1).

QUESTIONNAIRE ON HISTORICAL RADIOSONDE TEMPERATURE AND HUMIDITY INSTRUMENTS, METHODS OF OBSERVATION, AND REPORTING PRACTICES

1. Research and operational publications sometimes include valuable information and insights on changes in radiosonde systems which affect the data. Do any published reports document changes in your upper-air observing system or the effects of such changes? If so, please provide a complete reference for each and, if possible, please include a copy.

2. Station histories, which may include dates of implementation of changes in the radiosonde system or of changes in station location, are useful in interpretation of station data records. Are station histories available for upper-air stations? If so, please indicate in what form this information is stored and how it can be acquired.

3. Current and Past Practices: In each part of this question, please provide information on current practices first. Please note earlier practices that were different, with the applicable dates, going back to 1957 or earlier, if possible. If your information is incomplete or uncertain, please provide it anyway, noting the uncertainty. a) Temperature and Humidity Instruments: Introduction of new instruments usually leads to improved observations but can change the characteristics of the data record. Changes that affect biases are particularly important because they can be confused with climate changes. Please provide a history of the radiosondes (including the name of the manufacturer and the type if the manufacturer makes more than one type) that have been used by your Meteorological Service. Please provide the temperature and humidity sensor types (e.g., thermistor rod, carbon hygristor) and their accuracy and precision, if known. If different stations within the country have employed different instruments, please indicate which stations use(d) each instrument.

113 b) Methods of Observation: Changes in methods of observation can influence a data record; for example a change in observation time from daytime to nighttime will surely influence temperature and humidity measurements.

Please provide a history of any special methods of observation. Include calibration techniques, balloon tracking methods used. How many observations are (were) made daily and at what times?

c) Data Reporting Practices: Different nations employ different reporting practices for their own purposes, but these are not always known to other data users.

Please provide a history of any special reporting practices used by your Meteorological Service. For example, is there a minimum temperature, dewpoint, or humidity below which humidity data are not reported? Are there special adjustments or codes in the recorded values at high or low relative humidities.

d) Data Conversions: Moisture data reports depend on conversion algorithms, which may have changed over time or may differ among nations.

Please give a history of the algorithms used to convert relative humidity to dewpoint depression? Are any corrections applied to the data?

4. Please include here any additional information that you feel would be of use to data users. For example, are any future changes anticipated? Our purpose is to identify non meteorological signals in the data record; therefore, if you are aware of any possible sources of such a signal but did not mention them in previous responses, please do so here.

114 Appendix 3. List of VIZ Manufacturing Company Radiosondes

The table in this appendix lists radiosondes manufactured by VIZ Manufacturing Company since 1950. Not all these sondes were built for operational use. Where an entry is left blank, no information is available. Question marks indicate some uncertainty in the information. This information was compiled and graciously provided by Maurice Friedman, VIZ Manufacturing Company, Philadelphia, PA.

Some model numbers have three digits following the four digits and dash; the three digits have the following significance: 4XX: Standard baseline (not Accu-Lok) sensors 5XX: Factory baselined Accu-Lok sensors XXO: Built to meet U.S. Government specifications XXI or XX2: Commercial design (the only difference between government and commercial specifications is the inspection required by the government)

The following terms and abbreviations are used in the table:

Accu-Lok VIZ trade name for factory baselined sensors AES Atmospheric Environment Service (Canada) AMQ Army Meterological Query (?); a transponder system AMT Army Meterological Transmitter AN Army Navy ART automatic radio theodolite Baro. baroswitch (in the baroswitch/hypsometer combination (baro./hyps.) the baroswitch data is used until the two instruments agree (at about 20 hPa), then the hypsometer data is used for the rest of the sounding) BU Beukers Lab., Inc. (in about 1964, John Beukers suggested the use of Loran and Omega navigational systems for radiosondes; all Beukers radiosondes were manufactured by VIZ, and in 1980 VIZ bought BU) CFC chlorofluorocarbon (the CFC used is CFC-11, trichlorofluoromethane. Very early hypsometers used carbon disulfide rather than CFC-11) CMOS complementary metal oxide semiconductor Corr. bd. corrugated board Diam. diameter DOD Department of Defense Drlr. dereeler mechanism to allow gradual lengthening of the cord between the balloon and the sonde to avoid problems with a long cord at launch in windy conditions ESSA Environmental Sciences Services Administration GATE GARP [Global Atmospheric Research Program] Altantic Tropical Experiment GMD ground meteorological direction-fmding Hygr. hygristor Hyps. hypsometer IFYGL International Field Year for the Great Lakes LiCl lithium chloride humidity sensor

115 MDO Meteorological data oscillator .. MDS Meteorological data system (U.S. Army) mil 111 oooth inch Mk Mark ML ? MSS Meteorological Sounding System (used by the Air Force at various missile ranges) NOAA National Oceanic and Atmospheric Administration Nuvistor a cylindrical vacuum tube manufactured by RCA (used for 400 MHz transponders and responders) NWS National Weather Service PTU pressure, temperature, relative humidity RF radio frequency RDF radio direction fmder SCR-658 Signal Corps Radiodirection-fmder (403 MHz) SR solar radiation SRS solar radiation shield ss solid state UMQ ? USAF United States Air Force USWB United States Weather Bureau .. vac. tube vacuum tube V-700 ground system used in Israel (manufactured by Atir, Ltd., Petah Tikvah, Israel) WBRT Weather Bureau Radio Theodolite WE Western Electric W-8000 first fully digital VIZ ground system (a switching barosensor allowed pressure sensing at discrete intervals) W-9000 digital VIZ ground system with continuous pressure sensing system Xmtr transmitter Xpndr transponder Xstr transistor

116 - --- I VIZ Manufacturing Company Radiosondes: 1950-1992

NWS Years Freq. Pressure Stock Case Configuration and ~ode! Produced Description (MHz) ~emperature Humidity Sensor Sensor Wind Method No. National Stock No. Dimensions (inches) Comments No. Sensor

1949-1950 US Army ANIAMT-1 403 ~L-4191AM rod IML-418 LiCI Baroswitch SCR-658 Corrugated box First complete sonde 7.5x5x7.5 made by VIZ; rod Exposed temperature thermistor was (and is sensor still) made from clay from Kentucky 1000 1950-1958 US Army ANIAMT-2 403 !ML-4191AM rod IML-418 LiCI Baroswitch ISCR-658 DOD styrene case Tooled first Army styrene case in 1949 1001 1954-1955 US Army ANIAMT-4A 1680 !ML-4191AM rod IML-418 LiCl Baroswitch ANIGMD-1 DOD styrene case 1002 1951-1953 US Navy ANIAMT-7B ~3 ~L-4051AM rod ~L-379LiCI Baroswitch [Radar Paper case, inside duct 1003 1955-1957 ANIAMQ-9(XE1) 1680 ~L-4191AM rod ~L-476 carbon None ANIGMD-2 DOD styrene case Xpndr fw3 film 1004 1954-1955 US Army Wiresonde None, WE Glass bead Wet-dry WE beads None None Special case AN/UMQ-4 with r.vired ethered balloon 1005 1957-1965 ANIAMQ-9(XE2) 1680 !ML-4191AM rod !ML-476 carbon None ANIGMD-2 DOD styrene case 403 film 1013 1955-1957 US Army ANIAMT-4B 1680 !ML-4191AM rod ML-418 LiCl Baroswitch ANIGMD-1 DOD styrene case 1021 1958-1971 USWB (vac. tube) 403 ~L-4051AM rod Carbon ~ygr. Baroswitch SCR-658 004 6660-00-916-3327 Paper case,, inside duct [The carbon hygristor is made of carbon particles in an ethyl cellulose matrix 1022 1958-1971 USWB (vac. tube) 1680 !ML-4051 AM rod Carbon hygr. Baroswitch GMD-1 005 6660-00-878-7209 Paper case, inside duct 1023 1958- US Army ANIAMT-2A 403 !ML-4191 AM rod ML-418 LiCl Baroswitch SCR-658 DOD styrene case 1030 1958-- USWB (vac. tube) 72 ~L-4051 AM rod ML-379LiCI Baroswitch None. PTU IJ003 Paper case, inside duct only 1031 1958- USWB winds-only 1680 None None Baroswitch WBRT IJ005A Paper case, inside duct 1038 1956- US Army ANIAMT-12 1680 ~L-4191AM rod ML-476 carbon Baro./Hyps. DOD styrene case Carbon disulfide used as film !hyps. fluid 1042 1957-1960 US Army AN/AMT-4C 1680 fML-4191 AM rod Carbon hygr. Baroswitch ANIGMD-1 DOD styrene case 1045 1960- US Army ANIAMT-4D 1680 ~-4191AM rod Carbon hygr. ~aroswitch ~/GMD-1 DOD styrene case 1049 1960- US Navy rocketsonde 403 IML-4051 AM rod ML-379LiCI Aneroid, ~eciever Projectile for 4" rocket Launched from aircraft, Potentiomet RS-228 !under wing er 1051 1953-1960 US Navy ANIAMT-llB 403 ML-4051 AM rod ML-379LiCI Baroswitch Radar Very small plastic case 1056 1960 USWB (vac. tube) 1680 ML-4051 AM rod Carbon hygr. Baroswitch WBRTIGMD-1 Corr. bd. case, inside duct ------

117 1057 "1960 USWB (vac. tube) 403 ~L-405/ AM rod '--arbon hygr. Baroswitch SCR-658 Corr. bd. case, inside duct 1058 1960 USWB (vac. tube) 72.2 ML-405/AM rod Carbon hygr. Baroswitch Radar Corr. bd. case, inside Used for shipboard duct launches 1059 1960 USWB windsonde 1680 None None Baroswitch WBRT/GMD-1 Corr. bd. case, inside duct 1060 1960 US Navy AMT-ll(DX) 403 ~L-405/ AM rod ML-379 LiCl Baroswitch Very small plastic case 1062 1961 USWB (vac. tube) 1680 ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 Corr. bd. case, single op duct 1063 1961 . USWB (vac. tube) 1680 ML-405/AM rod Carbon hygr. Baro./Hyps. WBRT/GMD-1 Corr. bd. case, single op duct 1064 1961 USWB (vac. tube) 1680 None None Baroswitch WBRT/GMD-1 Corr. bd. case, single op duct 1065 1961 USWB (vac. tube) 403 ML-405/AM rod Carbon hygr. Baroswitch SCR-658 Corr. bd. case, single op duct 1066 1961 USWB (vac. tube) 403 ~L-405/ AM rod Carbon hygr. Baro./Hyps. SCR-658 Corr. bd. case, single op duct 1067 1961 USWB (vac. tube) 72.2 ~L-405/ AM rod Carbon hygr. Baroswitch Radar, Corr. bd. case, single shipboard op duct 1068 1961 USWB (vac. tube) 1680 ~-405/AM rod Carbon hygr. Baro./Hyps. WBRT/GMD-1 Corr. bd. case, single Includes Kuhn op duct radiometer for albedo· measurements 1069 1961 USWB (vac. tube) !"J3 ~L-40.:>/ AM rod Carbon hygr. Baroswitch SCR-658 Corr. bd. case, single Includes Kuhn op duct radiometer for albedo ·- measurements 1070 1961 AES (vac. tube) 107 Carbon hygr. Baroswitch AES, shipboard Corr. bd. case, single Shipboard use op duct 1071 1960-1969 USWB (vac. tube) 72.2 ~L-405/ AM rod Carbon hygr. Baroswitch None; PIU Corr. bd. case, single only op duct 1072 1963- USWB (vac. tube) 1680 ~L-405/ AM rod <.-arbon hygr. Baroswitch WBRT/GMD-1 Plastic, single air duct 1963, first use of plastic, single duct 1073 1963- USWB (vac. tube) 1680 ~L-405/ AM rod Carbon hygr. Baro./Hyps. WBRT/GMD-1 Plastic, single air duct 1074 1963- USWB (vac. tube) 1680 ~-4051AM rod Carbon hygr. Baroswitch WBRT/GMD-1 Plastic, single air duct 1075 1963- USWB (vac. tube)- 403 ~L-405/AM rod Carbon hygr. Baroswitch SCR-658 Plastic, single air duct 1076 1963- USWB (vac. tube, 1680 ~L-405/AM rod Carbon hygr. Baroswitch AN/GMD-2 Plastic, single air duct lxpndr) ~3 1077 1963- USWB (vac. tube) 72.2 ~L-405/ AM rod Carbon hygr. Baroswitch Radar, Plastic, single air duct shipboard 1078 1963- USWB (vac. tube, 403 ~L-405/AM rod Carbon hygr. Baroswitch Radar, Plastic, single air duct Paper box, pulsed RF pulsed) shipboard 1079 1963- USWB (vac. tube) 1680 ~L-405/ AM rod Carbon hygr. Baroswitch AN/GMD-2 Plastic, single air duct Used 6CW4 Nuvistor in 403 receiver -

118 1080 1963-1965 New Zealand 72.2 !ML-405/ AM rod Carbon hygr. Baroswitch fRadar Corr. bd. case, single op duct, 7.5x4.75x8.25 1081 1963 USWB (vac. tube) 403 IML-405/AM rod Carbon hygr. Baro./Hyps. SCR-658 Plastic, single air duct 1089 1963 US Army AN/AMT-4B 1680 !ML-419/ AM rod !ML-476 carbon Baroswitch AN/GMD-1 Corr. bd. single top duct pcmtr used 1U4 tube, film instead of CK5875 1090 r. 1964 US Army AN/AMT-40 1680 !ML-419/AM rod !ML-476 carbon Baroswitch AN/GMD-1 6660-542-1964 DOD styrene case film 1091 rt 1964-1971 us Army 1680 IML-419/AM rod !ML-476 carbon Baro./Hyps. AN/GMD-lA ~660-935-1455 DOD styrene case 1964, CFC-11 used in AN/AMT-12A film !hYP someter 1092 1965-1972 USWB (vac. tube) 1680 !ML-405/AM rod ~arbon hygr. Baroswitch WBRT/GMD-1 OllA 6685-01-106-83 96 Plastic, single air duct 1969, BOMEX first use of Accu-Lok 1093 1965-1972 USWB (vac. tube) 1680 !ML-405/ AM rod Carbon hygr. Baro./Hyps. WBRT/GMD-1 Plastic, single air duct 1095-410 1964-1972 USWB (vac. tube) 403 IML-405/ AM rod Carbon hygr. !Baroswitch ~CR-658 Plastic, single air duct 1096 1965-1972 USWB (vac. tube, 1680 !ML-405/ AM rod Carbon hygr. Baro./Hyps. AN/GMD-2 006A 6660-00-878-7215 Plastic, single air duct pcpndr/Hyps. lxpndr) 4o3 1097 1965-1972 USWB (vac. tube) 72.2 !ML-405/AM rod Carbon hygr. Baroswitch !Radar, Plastic, single air duct shipboard 1098 1965-1972 USWB (vac. tube, ~3 !ML-405/ AM rod Carbon hygr. Baroswitch !Radar, Plastic, single air duct ~ulsed) shipboard 1099 1965-1972 US ARMY AN/AMT-9 1680 IML-419/AM rod IML-476 carbon Computed AN/GMD-2 DOD styrene case film 1151 1968- US Army 403 IML-419/AM rod Carbon hygr. Baroswitch fRadar, Navy Very small plastic case Xmtr MDO, vac. tube AN/AMT-llE shipboard RF, carbonhumidty sensor 1190 1974- US Army AN/AMT-40 1680 !ML-419/AM rod !ML-476 carbon Baroswitch AN/GMD-lA 6660-00-542-1964 DOD styrene case film 1191 1974- us Army 1680 !ML-419/AM rod [ML-476 carbon Baroswitch AN/GMD-1A DOD styrene case Built for the 1974 AN/AMT-12A film Global Atmospheric Research Program, Altantic Tropical Experiment. Accu-Lok sensors 1192 1970- NOAA-NWS Xstr 1680 !ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 Plastic, dual SR air duct 10/3170 ESSA becomes !Moo NOAA 1193 1970- NOAA-NWS Hyps. 1680 !ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 Plastic, dual SRS air Introduced dual air duct duct in 1970 1195 1970- NOAA-NWS Xstr ~3 !ML-405/ AM rod Carbon hygr. Baroswitch fRadar Plastic, dual SRS air ~0 duct 1199 1970- NWS Xstr MDO/Xpndr 1680 Carbon hygr. Baroswitch AN/GMD-2 403 1205 1969-1970 NOAA-NWS Loran-C f4U3 IML-405/ AM rod Carbon hygr. Baroswitch Loran-C Plastic, dual SRS air duct L__ ~~-

119 1206 1969-1970 NOAA-NWS Omega 403 ML-405/AM rod Carbon hygr. Baroswitch Omega Plastic, dual SRS air duct 1207 1970 Decca receiver 403 ML-405/AM rod Carbon hygr. Baroswitch fR.adar Plastic, dual SRS air duct 1210 1970-1971 "Windrosonde" /Loran-C 403 Loran-C Dropsonde Beukers First dropsonde with Navaid (VIZ-BLI) 1211 1970-1971 "Windrosonde" /Omega 403 pmega Dropsonde Beukers 1220 1972-1993 NOAA-NWS Loran-C ~3 ML-405/AM rod Carbon hygr. Baroswitch Loran C Foam, 6x6x12, dual SRS 1220 series has solid duct state 403 MHz Xmtr 1221 1972- NOAA-NWS Omega 403 ML-405/AM rod '-arbon hygr. Baroswitch Omega Foam, 6x6Xl2, dual SRS duct 1223 1972-1973 Automet Loran-C 403 ML-405/AM rod Carbon hygr. Baroswitch Loran-C Foam, 6x6X12, dual IFYGL SRS duct 1224 1973 Automet Omega GATE [403 ML-405/AM rod Carbon hygr. Baroswitch Omega Foam, 6x6X12, dual ~RS duct 1239 Egypt, "Firefly" 403 ML-405/AM rod 1'-arbon hygr. Baroswitch fR.adar Foam, 6x6X12, dual SRS duct 1290 US Army AN/AMT-4 1680 ML-419/AM rod IML-476 carbon Baroswitch AN/GMD-1 DOD styrene case film 1291 US Army AN/AMT-12 1680 ML-419/AM rod IML-476 carbon Baroswitch AN/GMD-1 DOD styrene case film 1292-410 NOAA-NWS baseline 1680 ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 005 6660-00-878-7209 Plastic, dual SRS air duct 1292-510 NOAA-NWS Accu-Lok 1680 ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 Plastic, dual SRS air -. duct 1293 1969-1973 NOAA-NWS Hyps. 1680 ML-405/AM rod 1'-arbon hygr. Baroswitch WBRT/GMD-1 005B 6660-00-878-7214 Plastic, dual SRS air duct 1294 1969-1973 NOAA-NWS windsonde 1680 None None Baroswitch WBRT/GMD-1 Plastic, dual SRS air duct 1295 1969-1973 NOAA-NWS 403 ML-405/AM rod Carbon hygr. Baroswitch ~CR-658 004 6660-00-916-3327 Plastic, dual SRS air duct 1296 1969-1973 NOAA-NWS 1680 ML-405/AM rod Carbon hygr. Baro./Hyps. WBRT/GMD-1 ~006A 6660-00-878-7215 Plastic, dual SRS air Xpndr/Hyps. 403 ~uct 1298 1969-1973 NOAA-NWS 403 ML-405/AM rod Carbon hygr. Baroswitch fRadar ~004A 6660-00-878-7216 Plastic, dual SRS air Pulsed duct 1299 1969-1973 NOAA-NWS Xpndr 1680 ML-405/AM rod Carbon hygr. Baroswitch AN/GMD-2 ~006 6660-00-878-7206 Plastic, dual SRS air 403 Xpndr ~uct 1315- 1983-1987 NOAA-dropsonde 403.5 White Bead 1'-arbon hygr. Capacitive Omega [fube, 3.5 diam. x 18 Made for both NOAA aneroid long &USAF 1315- 1983- NOAA-dropsonde ~4.5 White Bead Carbon hygr. Capacitive Omega [fube, 3.5 diam. x 18 Made for both NOAA ~neroid long &USAF 1315- 1983- NOAA-dropsonde 405.5 White Bead 1'-arbon hygr. '-apacitive Omega [Tube, 3.5 diam. x 18 Made for both NOAA aneroid long &USAF ----

120 1323 1976 Automet Loran-C r:t03 IML-405/AM rod ~arbon hygr. Baroswitch Loran-C Foam, 6x6x12, dual SRS NowuseCMOS duct switching 1324 1976 Automet Omega rw3 IML-405/ AM rod ~arbon hygr. Baroswitch Omega Foam, 6x6xl2, dual SRS NowuseCMOS duct switching 1332 1976 Automet VLF/Omega rw3 ML-405/AM rod ~arbon hygr. Baroswitch VLF/Omega Foam, 6x6x12, dual SRS NowuseCMOS duct switching 1392-410 1975-1992 NWS, baseline 1680 ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 ;J030 6660-01-106-0484 Plastic, dual SRS air duct 1392-510 1975-1992 NWS, Accu-Lok 1680 ~-405/AM Carbon hygr. Baroswitch WBRT/GMD-1 031 6660-01-103-9121 Plastic, dual SRS air Accu-Lok, factory Accu-Lok iAccu-Lok duct baselined sensors 1393-410 1975-1992 NWS, hps. baseline 1680 ML-405/AM rod ~arbon hygr. Baro./Hyps. WBRT/GMD-1 036 Plastic, dual SRS air Field baselined sensors duct 1393-510 1975-1992 NWS, Hyps. Accu-Lok 1680 ML-405/AM ~arbon hygr. Baro./Hyps. WBRT/GMD-1 037 Plastic, dual SRS air Accu-Lok, factory Accu-Lok Accu-Lok duct baselined sensors 1394-410 1975-1992 NWS Windsonde 1680 None None Baroswitch WBRT/GMD-1 1395-410 1975-1992 NWS, baseline 403 ML-405/AM rod Carbon hygr. Baroswitch WBRT/GMD-1 NWS stopped using 403 MHz sondes 1395-510 1975-1992 NWS, Accu-Lok 403 ML-405/AM ~arbon hygr. Baroswitch WBRT/GMD-1 NWS stopped using 403 Accu-Lok Accu-Lok MHz sondes 1399-410 1975-1992 NWS/Xpndr, baseline 1680 ML-405/AM rod ~arbonhygr. Baroswitch WBRT/GMD-2 1399-510 1975-1992 NWS/Xpndr, Accu-Lok 1680 ML-405/AM ~arbon hygr. Baroswitch WBRT/GMD-2 Accu-Lok Accu-Lok 1492-510 NWS/ART/"A"/Accu- 1680 ML-405/AM ~arbon hygr. Baroswitch WBRT/GMD-1 Plastic, dual SRS air Lok Accu-Lok Accu-Lok duct 1492-512 -: Time sequenced 1/2 s 1680 ML-405/AM rod ~arbon hygr. .. Baroswitch GMD-1, V-700 Used by Israel Ministry of Defence 1492-520 NWS/ART/"B"/Accu- 1680 ML-405/AM Carbon hygr. Baroswitch WBRT/GMD-1 060 "B" sonde foam case Same as model 1492- Lok Accu-Lok Accu-Lok 6-5/8x4x12-1/2 510 but with modified case, including inside humidity duct 1492-522 Time sequenced 1/2 aec 1680 ML-405/AM ~arbon hygr. Baroswitch GMD-1, Used in Turkey Accu-Lok !RD-65, 1507-510 1980-1992 Mki!Digital/PTU 403 ML-405/AM ~arbon hygr. Baroswitch W-8000, PTU Accu-Lok Accu-Lok only 1523-510 1980-1992 Mkl/Digitai/Loran-C 403 ML-405/AM ~arbon hygr. Baroswitch W-8000,Loran Accu-Lok Accu-Lok 1524-510 1980-1992 Mki!Digitai/Omega 403 ML-405/AM ~arbon hygr. Baroswitch W-8000,0mega Accu-Lok Accu-Lok 1540-510 1992 Mkii/Digitai/PTU 1680 40 mil rod/Accu- ~arbon hygr. Capacitive VIZ W-9000 (MDS) Lok Accu-Lok sensor 1540-511 1992 !MkiiiDigitai/PTU 1680 4U mil rod/Accu- ~arbon hygr. Capacitive VIZ W-9000 Mkll MICROSONDE Lok Accu-Lok sensor case -----

121 1540-513 1992 [MkiiiDiglta1 Loran-C 1680 40 mi1 rod/Accu- Carbon hygr. Capacitive jVIZ W-9000 Lok Accu-Lok sensor 1540-514 1992 [MklliDigital Omega 1680 40 mil rod/Accu- ~arbon hygr. .... apacitive IVIZ W-9000 Lok !Accu-Lok sensor 1540-522 1992 IMklliDigital PIU 1680 40 mil rod/Accu- L.arbon hygr. '-apacitive VIZ W-9000 Has altitude-settab le jw/cutoff Lok Accu-Lok sensor ~utoff 1540-523 1992 [MklliDigital PIU and 1680 40 mil rod/ Accu- Carbon hygr. Capacitive VIZ W-9000 Ozone Lok Accu-Lok sensor 1540-525 1992 [Mkll/Digital PIU w/o 1680 40 mil rod/Accu- Carbon hygr. Capacitive IVIZ W-9000 Drlr. Lok !Accu-Lok sensor 1540-526 1992 [Mkll/Digital PIU 4 1680 40 mil rod/Accu- Carbon hygr. <...apacitive IVIZ W-9000 inputs Lok Accu-Lok sensor 1540-528 1992 [MklliDigital Loran 1680 40 mil rod/Accu- 1'-arbon hygr. o....apacitive fVIZ W-9000 fTwo black, one white, ~ thermistors Lok Accu-Lok sensor pne aluminum !thermistor. Designed ifor determining solar radiation corrections. 1543-510 1992 Mkll/Loran-C (MDS) 403 40 mil rod/Accu- 1'-arbon hygr. 1'-apacitive IVIZ W-9000 Mkll MICROSONDE Lok Accu-Lok sensor case 1543-511 1992 Mkll/Lorsn-C 403. 40 mil rod/Accu- 1'-arbon hygr. 1'-apacitive IVIZ W-9000 Lok Accu-Lok sensor 1543-522 1992 Mkll/Loran-C w/cutoff 403 40 mil rod/Accu- Carbon hygr. 1'-apacitive IVIZ W-9000 Has altitude-settable Lok Accu-Lok sensor cutoff 1543-523 1992 Mkll/Lorsn-C w/Ozone 403 40 mil rod/Accu- ~arbon hygr. 1'-apacitive IVIZ W-9000 . Lok Accu-Lok sensor 1543-525 1992 Mkll/Loran-C w/o Drlr. 403 40 mil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 Lok Accu-Lok sensor 1543-526 1992 Mkll/Loran-C 4 inputs 403 40 mil rod/Accu- 1'-arbon hygr. ~apacitive fVIZ W-9000 Lok Accu-Lok sensor 1543-528 1992 Mkll/Loran-C 4 403 40 mil rod/Accu- 1'-arbon hygr. Capacitive fVIZ W-9000 thermistors Lok Accu-Lok sensor 1544-511 1992 Mkll/Omega 1403 40 mil rod/Accu- 1'-arbon hygr. Capacitive VIZ W-9000 Mkll MICROSONDE Lok Accu-Lok sensor case 1544-522 1992 Mkll/Omega w/cutoff 403 40 mil rod/Accu- 1'-arbon hygr. Capacitive jVIZ W-9000 Lok Accu-Lok sensor 1544-523 1992 Mkll/Omega w/Ozone 403 40 mil rod/Accu- Carbon hygr. Capacitive IYIZ W-9000 Lok Accu-Lok sensor 1544-525 1992 [Mkll/Omega w/o Drlr. [403 40 mil rod/Accu- 1'-arbon hygr. Capacitive IVIZ W-9000 Lok Accu-Lok sensor 1544-526 1992 [Mkll/Omega 4 inputs 403 40 mil rod/Accu- Carbon hygr. Capacitive IVIZ W-9000 Lok Accu-Lok sensor 1545-510 1992 [Mkll!VLF/Omega [403 40 mil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 (MDS) Lok Accu-Lok sensor -- -

122 1545-511 1992 !MkiiiVLF/Omega 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 Lok Accu-Lok sensor 1545-522 1992 !MkiiiVLF/Omega 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 ~/cutoff Lok Accu-Lok sensor 1545-525 1992 !MkiiiVLF/Omega w/o 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 Mkll MICROSONDE Drlr. Lok Accu-Lok sensor case 1545-526 1992 !MkiiiVLF/Omega 4 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 inputs Lok Accu-Lok sensor 1547-511 1992 !MkiiiPTU 403 40 rnil rod/ Accu- Carbon hygr. Capacitive VIZ W-9000 Mkll MICROSONDE Lok Accu-Lok sensor case 1547-522 1992 MkiiiPTU w/cutoff 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 Lok Accu-Lok sensor 1547-523 1992 MkiiiPTU w/Ozone 403 40 rnil rod/Accu- 1'-arbon hygr...... apacitive VIZ W-9000 Lok Accu-Lok sensor 1547-525 1992 MkiiiPTU w/o Drlr. 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 Lok Accu-Lok sensor 1547-526 1992 MkiiiPTU 4 inputs 403 40 rnil rod/Accu- Carbon hygr. Capacitive VIZ W-9000 ' Lok Accu-Lok sensor 1560-510 1985-1992 US Army MDS RDF 1680 ML-405/AM rod Carbon hygr. Baroswitch MDS System 6660- Special case, top duct 1563-510 1985-1992 USArrnyMDS 403 ML-405/AM rod Carbon hygr. Baroswitch MDS System 6660- Special case, top duct Loran-C ! 1564-510 1985-1992 US Army MDS Omega 403 ML-405/ AM rod 1'-arbon hygr. Baroswitch MDS System 6660- Special case, top duct 1799-310 USAFXpndr 1680 None None None GMD-SMSS Special case, dual Windsonde system ~urnidity duct 1799-610 < USAFXpndr 1680 13 rnil diam. 1'-arbon hygr. None GMD-SMSS Radiosonde alurnized bead system

123

- 1 -

LIST OF PUBLICATIONS in the INSTRUMENTS AND OBSERVING METHODS REPORTS SERIES

Report No. 1 Automated Meteorological Systems. Papers presented at the Technical Conference on Evolution and Standardization of Observing Techniques in Light of Automation (Norrkoping, Sweden, 1980)

Report No. 2 Instrument Development Inquiry (Third Edition), 1980

Report No. 3 Lower Tropospheric Data Compatibility. Low-level Intercomparison Experiment (USA, 1979)

_Report No. 4 WMO Equipment Survey - Meteorological Satellite Ground-based Receiving Equipment, 1980

Report No. 5 WMO Catalogue of Radiosondes in Use by Members, 1981 (out of print)

Report No. 6 Preliminary Analysis of a Questionnaire on Aerodrome Meteorological Measurements By M. M. Etienne, 1981

Report No. 7 The Meteorological Use of Navaid Systems - A brief technical assessment By A. Lange, 1981

Report No. 8 Report on Meteorological Radars By G. A. Clift, 1981

Report No. 9 Papers presented at the Second WMO Technical Conference on Instruments and Methods of Observation (TECIM0-11) (Mexico City, 1981)

Report No. 10 Radiation Effects on the WMO Reference Psychrometer in the Field By R. G. Wylie and T. Lalas, 1981

Report No. 11 WMO Catalogue of Radiosondes in Use by Members, 1982

Report No. 12 Meteorological Observations by Laser Indirect Sensing Techniques By A. 0. van Gysegem, 1982

Report No. 13 The Use of Hydrogen for Inflation of Meteorological Balloons, 1982

Report No. 14 Summary Results of a 1978 Survey of Calibration Facilities and of Tests and Evaluation of Instruments (out of print) - 2 -

Report No. 15 Papers presented at the WMO Technical Conference on Instruments and Cost Effective Meteorological Observations (TECEMO), (N oordwijkerhout, Netherlands, 1984)

Report No. 16 Comparison of Pyranometers and Electronic Sunshine Duration (TD 146) Recorders of RA VI (Budapest, 1984) By G. Major, 1986

Report No. 17 International Comparison of National Precipitation Gauges with (TD 38) a Reference Pit Gauge, By B. Sevruk and W. R. Hamon, 1984

Report No. 18 Guidance Material on Meteorological Instruments Suitable for (TD 112) Use in Developing Countries By E. S. Engawi, 1986

Report No. 19 Some General Considerations and Specific Examples in the Design (TD 230) of Algorithms for Synoptic Automatic Weather Stations By D. T. Acheson, 1987

Report No. 20 Stations Automatiques a Faible Cout (TD 177) By P. Viton, 1986

Report No. 21 Algorithms for Automatic Aerological Soundings (TD 175) By A. H. Hooper, 1986

Report No. 22 Papers presented at the WMO Technical Conference on Instruments (TD 50) and Methods of Observation (TECIMO-III) (Ottawa, 1985)

Report No. 23 Keynote papers presented at the Third WMO Technical Conference (TD 51) on Instruments and Methods of Observation (TECIMO-III) (Ottawa, 1985)

Report No. 24 Instruments Development Inquiry (Fourth Edition) (TD 231) By E. Prokhorov, 1987

Report No. 25 Papers presented at the Workshop on the Correction of· (TD 104) Precipitation Measurements (Zurich, Switzerland, 1985)

Report No. 26 Lectures presented at the Workshop for Instrument Specialists, (Buenos Aires 1984) (in Spanish) {out of print)

Report No. 27 WMO Catalogue of Radiosondes and Upper-Air Wind Systems in Use (TD 176) by Members, 1986

Report No. 28 WMO International Radiosonde· Comparison, Phase I, · (TD 174) (Beaufort Park, UK, 1984) By A. H. Hooper, 1986

Report No. 29 WMO International Radiosonde Intercomparison, Phase II) (TD 312) (Wallops Island, USA, 1985)' By F. Schmidlin - 3 -

Report No. 30 WMO International Radiosonde Comparison (UK, 1984 I USA, 1985) (TD 195) By J. Nash and F. Schmidlin, 1987 (out of print)

Report No. 31 The Measurement of Gustiness at Routine Wind Stations -A Review By A. C. M. Beljaars, 1987

Report No. 32 WMO International Ceilometer Intercomparison (UK, 1986) (TD 217) By D. W. Jones, M. Ouldridge and D. J. Painting, 1988

Report No. 33 Papers presented at the WMO Technical Conference on Instruments (TD 222) and Methods of Observation (TEC0-1988) (Leipzig, German Democratic Republic, 1988)

Report No. 34 WMO Assmann Aspiration Psychrometer Intercomparison (TD 289) (Potsdam, German Democratic Republic, 1987) By D. Sonntag, 1989

Report No. 35 Papers presented at the Fourth WMO Technical Conference on (TD 303) Instruments and Methods of Observation (TECIMO-IV) (Brussels, 1989)

Report No. 36 Compatibility of Radiosonde Geopotential Measurements (TD 344) By M. Kitchen, 1988

Report No. 37 Information on Weather Radars used by WMO Members (TD 309) By M. Gilet, 1989

Report No. 38 WMO International Hygrometer Intercomparison (TD 316) (Oslo, Norway, 1989) By J. Skaar, K. Hegg, T. Moe, K. Smedstud

Report No. 39 Catalogue of National Standard Precipitation Gauges (TD 313) By B. Sevruk and S. Klemm, 1989

Report No. 40 WMO International Radiosonde Comparison, Phase Ill (TD 451) (Dzhambul, USSR, 1989) By A. Ivanov, A. Kats, S. Kumosenko, J. Nash, and N. Zaitseva

Report No. 41 First WMO International lntercomparison of Visibility (TD 401) Measurements, United Kingdom, 1989) By D. J. Griggs, D. W. Jones, M. Ouldridge, W. R. Sparks

Report No. 42 WMO Automatic Sunshine Duration Measurement Comparison (Hamburg, Federal·Republic of Germany, .1989) By K. Dehne (In preparation)

Report No. 43 First WMO Regional Pyrheliometer Comparison of RA IIIRA V (TD 308) (Tokyo, Japan, 1989) - 4 -

Report No. 44 First WMO Regional Pyrheliometer Comparison of RA N (TD 345) (Ensenada, Mexico, 1989) By I. Galindo

· Report No. 45 Analysis of Instrument Calibration Methods used by Members (TD 310) By H. Doring, 1989

Report No. 46 WMO Digital Barometer Comparison (De Bilt, Netherlands, 1989) (TD 474) By J. van der Meulen

Report No. 47 Reports of the CIMO Working Group on Surface Measurements (TD 452) Guidance on the Establishment of Algorithms for Use in Synoptic Automatic Weather Stations - Processing of Surface Wind Data - By D. Painting, 1991

Report No. 48 International Workshop on Precipitation Measurements (TD 328) (St. Moritz, Switzerland, 1989) .

Report No. 49 Papers presented at the WMO Technical Conference on Instruments (TD 462) and Methods of Observation (TEC0-92) (Vienna, Austria, 1992)

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