The West Texas Mesonet: a Technical Overview

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The West Texas Mesonet: A Technical Overview

J. L. SCHROEDER,W.S.BURGETT,K.B.HAYNIE, AND I. SONMEZ Wind Science and Engineering Research Program, Texas Tech University, Lubbock, Texas

G. D. SKWIRA National Weather Service, Lubbock, Texas

A. L. DOGGETT Applied Insurance Research, Boston, Massachusetts

J. W. LIPE National Weather Service, Lubbock, Texas

(Manuscript received 2 March 2004, in final form 1 July 2004)

ABSTRACT The West Texas Mesonet originated in 1999 as a project of Texas Tech University. The mesonet consists of 40 automated surface meteorological stations, two atmospheric profilers, and one upper-air sounding system. Each surface station measures up to 15 meteorological and 10 agricultural parameters over an observation period of 5 and 15 min, respectively. The mesonet uses a combination of radio, cell phone, landline phone, and serial server (Internet) communication systems to relay data back to the base station at Reese Technology Center (formerly Reese Air Force Base), Texas. Data are transmitted through the radio network every 5 min for most meteorological data and every 15 min for agricultural data. For stations located outside of the radio network, phone systems transmit data every 30–60 min. The archive includes data received through the various communication systems, as well as data downloaded in the field from each station during regularly scheduled maintenance visits. Quality assurance/control (QA/QC) tests effectively flag data for manual review from a decision maker. The QA/QC flags and review decisions are then added to the database. All data are available free of charge; real-time data are available on the West Texas Mesonet Web page, and an interface to access the data archive is currently being developed.

1. Introduction for a statewide Texas Mesonet, currently (as of January 2004) consists of 40 automated surface meteorological The West Texas Mesonet (WTM) is a joint partner- stations, two atmospheric profilers, and one upper-air ship between the Atmospheric Science Group and sounding system. All, except one, of the WTM surface Wind Science and Engineering Research Center at stations are within 250 km of Lubbock, Texas (see Fig. Texas Tech University. Originating in 1999, the main 1). Each surface station measures up to 28 different goal of the WTM is to provide free, timely, and accu- parameters with an observation period of 5 min for rate meteorological and agricultural data to all resi- meteorological data (e.g., air temperature, humidity, dents of the South Plains/Rolling Plains region of west- etc.) and 15 min for agricultural data (e.g., soil tempera- ern Texas. The WTM has a close partnership with the ture, soil moisture content, etc.). All real-time data National Weather Service (NWS) offices in Lubbock, from the surface stations are available free of charge Midland, Amarillo, and Fort Worth, and provides valu- online at the WTM Web page at www.mesonet.ttu.edu. able real-time data to aid in warning verification for the The WTM also includes two atmospheric profilers lo- NWS in the data-sparse region of western Texas. cated at Reese Technology Center, Texas. The WTM, originally intended to be a pilot project 2. West Texas Mesonet surface Corresponding author address: J. L. Schroeder, Dept. of Geo- observation systems sciences, Texas Tech University, Box 42101, Lubbock, TX 79409- 2101. The WTM project was modeled after the Oklahoma E-mail: [email protected] Mesonet (Brock et al. 1995). The site selection specifi-

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Stations were located at strategic points to act as both full mesonet stations and radio repeaters. This approach required two or three mesonet stations in one county while other counties have only one station. The WTM has a dense network of stations aligned north– south near the Caprock Escarpment to aid in radio reception between the stations on and off the Caprock. There are approximately 750 m in elevation change between the farthest northwest and southeast stations. Again this required some creative positioning of stations to aid in radio reception. The second constraint in site selection was to maintain correct wind exposure and site slope. For each site, the Oklahoma Mesonet guidelines of maintaining a site slope of less than 5° and limiting obstruction heights to 0.05 times the distance between the obstruction and the anemometer were used (Brock et al. 1995). Occasion- ally this requirement has demanded the removal of mesquite and other small trees that violate the wind exposure guidelines from around the site. The third constraint in site selection involved landowners providing the site free of charge. Approxi- mately two-thirds of the WTM sites are on public land owned by either a local city or county. The remaining sites are on privately owned land. Landowners were

FIG. 1. Map of West Texas Mesonet stations with WTM asked to refrain from any major disruption in the sur- four-letter IDs. rounding land characteristics for a minimum of 10 yr. Permission was also obtained to access each site from each landowner in all weather conditions and at any cations, site layout, and instrumentation selection of the time of the day. WTM are nearly identical to those used by the Okla- b. Site layout and details homa Mesonet (Shafer et al. 1993). The original proposal for the WTM required the installation of at least The layout of each mesonet station was modeled af- one mesonet station per county in a 28-county region ter the Oklahoma Mesonet with only minor differences surrounding Lubbock, Texas. There are currently 40 in sensor positioning (see Figs. 2 and 3 for site sche- stations in 28 counties as of January 2004. At least three matics). Each station has a fenced-in 10 m by 10 m plot additional WTM stations are planned for completion of land with a 10 m tall, guyed aluminum tower. The prior to the end of 2004. tower is hinged and can easily be lowered by two per- sonnel for sensor replacement and maintenance. A 70 cm wide by 70 cm deep concrete base was used to se- a. Site selection cure the tower with three guy wires used for additional The WTM covers two distinct geographic areas in support. western Texas. A flat plateau region west of the Ca- Each station uses solar panels to charge several deep- prock Escarpment dominates the South Plains region cycle gel-type marine batteries for power. The number that surrounds Lubbock. This area has a significant of solar panels and batteries at a site varies depending amount of irrigated agricultural production (mostly cot- on the amount of radio repeater traffic at the individual ton) with a limited population outside of the main city location. An average site has two 20-Wsolar panels of Lubbock. The land is very flat with minimal wind mounted with a south exposure and two deep-cycle ma- obstructions. The land east of the Caprock escarpment rine batteries. Several major repeater sites have two is called the Rolling Plains region, which is character- 50-W solar panels and four deep-cycle marine batteries ized by small hills and a very sparse population. This for power. To minimize shading on sensors, the solar area is ranch country; again it contains only minimal panels are mounted approximately half way up the wind obstructions. tower. No more than two 50-W solar panels are There were three main constraints in determining mounted on the tower because of wind loading con- site selection in the above regional area. The first con- cerns. If additional solar panels are needed, they are straint was to maintain a station spacing of approxi- mounted at ground level approximately 6 m away from mately 35 km throughout the network while satisfying the tower itself. the physical constraints of a line of sight radio network. The rain gauge (with a wind screen), soil tempera-

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FIG. 2. Elevation view of a typical West Texas Mesonet station. The 2-m temperature probe is not easily depicted given its location and has been omitted. Please see the plan view (Fig. 3) for more information. ture, and moisture content sensors are the only instru- are added for support. For those sites with no cattle, ments not attached directly to the tower. The other regular hog fencing was used with minimal fence posts. sensors are mounted on boom arms at different levels Tumbleweeds accumulate both inside and outside the on the tower (see Fig. 4). All wiring from the off-tower fenced-in area. These tumbleweeds can accumulate to sensors is routed through PVC pipe and buried under- significant depths inside the fenced-in area during the ground. The rain gauge is mounted to a 45 cm square spring months. At times, the tumbleweeds have concrete pad that is 20 cm above ground level to mini- blocked rain gauges and broken low-level sensors at mize flooding problems from heavy rainfall events. The several WTM locations. Tumbleweed removal is there- natural and bare soil temperature/moisture content fore part of the maintenance schedule for each site. plots are marked with treated lumber to identify their Animal damage to low-level sensors and wiring is a location during mowing. major problem. There is a significant concentration of The majority of the WTM sites are located in rural black-tailed prairie dogs on the South Plains region of areas, which at times are surrounded by cattle. There- western Texas. Prairie dogs have chewed through any fore, the fences had to be made of barbwire with stout unprotected wiring near or below ground level. Addi- fence posts. All fence posts are anchored into the tional protection has been provided to the low-level ground with concrete, and additional dead-man braces sensor wiring in the form of PVC conduit to minimize

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FIG. 3. Plan view of a typical West Texas Mesonet station. the damage. Predatory birds (hawks, owls, etc.) have and other agricultural sensors are not available at every also damaged sensors on boom arms mounted on the site. See Table 1 for a complete list of sensors, and tower and destroyed wiring. Additional protection Table 2 for sensor characteristics, accuracies, and has been provided to sensor wiring and additional dataset resolutions. space has been allocated on various different boom arms for the birds to roost without damaging individual 1) DATALOGGERS sensors. The WTM uses a Campbell Scientific CR23X data- Maintenance at each site is performed every two logger with one megabyte of extended memory. Each months during regularly scheduled visits. Regularly datalogger records a 5-min observation from each of scheduled maintenance includes mowing the grass, re- the meteorological sensors and a 15-min observation moving debris, testing and calibrating instrumentation, from each of the agricultural sensors. Sampling inter- and downloading data from the datalogger. The down- vals vary from 3 to 60 s depending on the sensor. Data loaded data are considered to be the official data ar- are stored in the logger in the 5- and 15-min observa- chive, as data are occasionally lost during radio and tion format. Up to 78 days of data can be stored in the phone transmissions. circular memory buffer of each logger before data are lost. Each datalogger has two 6-V backup batteries in c. Instrumentation and data acquisition equipment case power is lost from the main deep-cycle marine Each WTM station has a standard set of meteoro- batteries. This battery system is separate from the main logical sensors at identical positions on each tower. Soil batteries and can power the datalogger for approxi-

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from the agricultural community for low-level wind data for crop spraying. The 2-m anemometer is an R.M. Young 03103 Wind Sentry. Only 5-min average wind speeds are recorded by the datalogger for this sensor. While the 2-m peak gust information would be benefi- cial for providing QA/QC checks on the data collected from the 10-m anemometer, it is currently not recorded because of radio transmission/power limitations.

3) TEMPERATURE AND RELATIVE HUMIDITY PROBES The primary temperature and relative humidity sensor is the Vaisala HMP45C (modified by Campbell Sci- entific) located at 1.5-m AGL (WMO 1983). The HMP45C is mounted in an unaspirated 12-plate radiation shield that is positioned 0.9 m away from the tower. This unit is very reliable and has long-term stability. Additionally, Campbell Scientific 107 Temperature (thermistor-type) probes were installed at both the 9- FIG. 4. Photograph of the West Texas Mesonet site at Snyder 3E (SNYD). and 2-m level. These sensors are mounted in a nonaspirated 6-plate radiation shield that is positioned 0.6 m away from the tower. The use of nonaspirated radiation mately one month. These batteries help prevent the shields enables small radiation-induced errors to occur loss of data acquisition at each site. in the temperature measurements, especially in rela- tively calm conditions with low sun angles, high surface 2) ANEMOMETERS albedos, and high insolation. These errors have been The primary wind sensor employed at each WTM documented in a number of publications including site is an R. M. Young 05103 Wind Monitor located at Brotzge and Crawford (2000) and Richardson (1995). the 10-m height AGL (WMO 1983). This propeller- type anemometer measures both wind speed and direc- 4) SOLAR RADIATION tion. The information from this anemometer is used to Due to cost restraints, the WTM uses two types of provide each site’s average wind speed and direction pyranometers to measure incoming solar radiation. The and peak gust. Standard deviations of the wind speed Kipp and Zonen SP-Lite pyranometer is a third-class and direction are also generated using the information pyranometer used at the majority of stations. These from this anemometer. An additional anemometer was units are inexpensive and provide reliable estimates of added to each site at the 2-m level to satisfy requests incoming solar radiation. The Kipp and Zonen CM-3

TABLE 1. West Texas Mesonet equipment/sensors. Sensor Model Height AGL (m) Datalogger Campbell Scientific CR23X 1 Anemometer R.M. Young 05103 propeller type 10 R.M. Young 03103 cup type 2 Temperature/humidity Vaisala HMP45C with 12-plate shield 1.5 Temperature Campbell Scientific 107-L w/6-plate shield 2, 9 Temperature—soil Campbell Scientific 107-L Ϫ0.05, Ϫ0.20* Ϫ0.05, Ϫ0.1, Ϫ0.2** Soil moisture Campbell Scientific 615-L Ϫ0.05, Ϫ0.2, Ϫ0.6, Ϫ0.75 Pyranometers Kipp and Zonen SP-Lite, CM-3, CM21 2 Rain gauge Hydrological Services TB-3 and TB-4 w/screen 0.6 Barometer Vaisala PTB220B digital 0.75 Leaf wetness Campbell Scientific 237-L 0.5 Solar panels Solarex 20 and 50-W with external regulators 5.5 Radio communications MCC 545 100-W digital packet radio 1 Radio antenna Decibel DB212 dipole 8 Cell phone Motorola 3-W transceiver 1 Cell phone antenna Decibel ASP962 8-dB 4.5 Modem Campbell Scientific COM210 Analog 1 Micro serial server Campbell Scientific NL100 NA

* Bare soil. ** Natural soil.

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TABLE 2. West Texas Mesonet sensor characteristics, accuracy, and data resolution. Sensor Characteristics Sensor accuracy Dataset resolution 10-m wind speed 1–60msϪ1 Ϯ2% 0.03 m sϪ1 10-m wind direction 0°–355° 3° 0.05° 9-m temperature Ϫ30°–50°C Ϯ0.4°C 0.01°C 2-m temperature Ϫ30°–50°C Ϯ0.4°C 0.01°C 2-m wind speed 0.5–50msϪ1 Ϯ2% 0.2 m sϪ1 2-m solar radiation SP-Lite Silicon photo diode Ϯ5% 0.1 W mϪ2 CM-3 Second-class pyranometer Ϯ5% 0.1 W mϪ2 1.5-m temperature Ϫ40°–60°C Ϯ0.4°C 0.01°C 1.5-m relative humidity 0%–100% Ϯ3% 0.1% Barometric pressure 500–1100 mb 0.2 mb 0.01 mb Rain gauge Siphon, tipping-bucket 200-mm funnel Ϯ2% 0.01 in (0.25 mm) Leaf wetness 0–100 (dimensionless) NA 0.1 Soil temperature Ϫ30°–50°C Ϯ0.4°C 0.05°C Soil moisture Square wave output 0.7–1.6 ms Ϯ2.5% VWC* 0.1 VWC*

* Volumetric water content. pyranometer is used on mesonet stations in a nine- levels under natural and bare soil conditions. The natu- county radius surrounding Lubbock. These are classi- ral soil plot has probes at 5, 10, and 20 cm below ground fied as a second-class pyranometer by the WMO level. The bare soil plot has probes at 5 and 20 cm (WMO 1983) and provide better estimates of incoming below ground level. The Campbell Scientific 615 Water solar radiation. All mesonet pyranometers are returned Content Reflectometer is used to measure the volumet- to the manufacturer for calibration. ric water content at 5, 20, 60, and 75 cm below ground level. The reflectometer creates a square wave output 5) RAINFALL MEASUREMENTS that when combined with different calibration equa- The primary rain gauge in the WTM is the Hydro- tions, based on soil type, density, and conductivity val- logical Services TB3 siphon tipping-bucket rain gauge. ues at each depth, is used to estimate the water content. This rain gauge has a 200-mm diameter receiver with a Soil samples for the various levels were given to a pri- 0.0254-cm calibrated bucket to measure rainfall. A vate laboratory that generated soil conductivity values. large portion of the gauge is made of aluminum, which These values are then applied to the datalogger pro- has a higher survivability in hailstorms than the stan- gram at each site to generate correct readings. At times, dard plastic tipping-bucket gauge. adjustments are made following heavy rain events, The top of the TB3 gauge is located at the recom- which yield saturated soil conditions. Soil temperature mended height of 0.6-m AGL (Brock et al. 1995). A and moisture data are not available for all WTM sta- NovaLynx Alter style windscreen surrounds each TB3 tions. rain gauge. The TB3 rain gauge is not heated and will 8) LEAF WETNESS SENSOR not measure the correct amount of precipitation in snow or freezing rain events. Additional TB4 model The Campbell Scientific 237 Leaf Wetness sensor is rain gauges will be added to the WTM this year. The used to provide an estimate of moisture on plants TB3 and TB4 model rain gauges are very similar with (Gillespie and Kidd 1978). The WTM positions the sen- only minor changes in design. The TB4 does include a sor at 50-cm AGL on the north-facing side of the tower. plastic base, but a special hail shield has been designed This was chosen to simulate droplet formation on ma- to protect the nonmetallic exterior. ture cotton plants (shady side). Individuals from the agricultural community use these data to determine 6) BAROMETIC PRESSURE when to spray their crops. Data from the leaf wetness The WTM uses a Vaisala PTB220 Class B digital sensor can also be used to determine when dew and fog barometer to measure station pressure at each site. The will develop. barometer is mounted inside the datalogger enclosure d. Instrumentation calibration box at a height of 0.75-m AGL. Calculations of altim- eter and sea level pressure are not generated at each Given funding limitations, the WTM only provides site. The average station pressure over a 5-min period is in-house calibration of two sensor types: anemometers currently the only pressure value recorded in the ar- and rain gauges. All other instrumentation is periodi- chive. cally returned to the manufacturer for calibration.

7) SOIL TEMPERATURE AND MOISTURE 3. Boundary layer profilers The Campbell Scientific 107 (thermistor-type) probe The Vaisala LAP-3000 radar profiler with RASS is is used to measure soil temperature values at different used to obtain estimates of wind speed, wind direction,

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4. Atmospheric sounding system A Vaisala DigiCORA III upper-air sounding system is employed to launch meteorological soundings from Reese Center during interesting weather events. The DigiCORA III system records a variety of atmospheric parameters every 1.5 s. The system is flexible enough to allow both GPS and LORAN-ready radiosondes. Soundings are generally launched in response to requests from the NWS or in support of local and regional research projects. All data from the Reese Center launches are available online at the WTM Web page.

5. Communications

One goal of the WTM is to make 5-min observations FIG. 5. West Texas Mesonet data flow from remote stations to available, in a real-time environment, to a wide variety users. of users. An approach similar to the Oklahoma Meso- net (Brock et al. 1995) was proposed to the State of Texas using the Texas Law Enforcement Telecommu- work consists of one radio. Because of line-of-site re- nications System (TLETS) for two-way communication strictions, several stations double as repeaters through- between a data collection computer and remote meso- out the current network. As of this writing, 10 of the 28 net stations. This proposal, however, was denied and WTM stations in the radio communication network other alternatives were pursued. Initially, recurring serve as repeaters. Two nonmesonet station repeaters costs of any sort were not part of the WTM budget. are located in strategic areas of the radio communica- Therefore, emphasis was placed on a two-way commu- tion network. nications system that would be reliable and have a reasonable bandwidth, but not incur monthly fees. A sum- b. Cellular phone mary of the current methods used for data transmission is provided in Fig. 5. In the midst of constructing a suitable radio communication network, it became evident that communica- a. Extended Line of Sight Radio (ELOS) tion via radio would not be feasible in the most distant counties of the WTM domain. Cellular phone technol- Satellites were never seriously considered as a viable ogy provided a short-term, alternative solution for col- method for two-way communications. Generally slow lecting data from remote WTM stations beyond the data rates, cumbersome communication methods radio communication network. Acceptable bandwidth, (Brock et al. 1995), and recurring expenses were unac- short connection times, and a favorable agreement with ceptable. ELOS communication provided a reasonable a local cellular phone company provide access to re- alternative with limited recurring expenses, but the mote stations at an affordable cost. As of this writing, availability of a high antenna site became a necessity. A eight WTM stations employ cellular phone connec- 73-m tower was erected by the Wind Science and En- tions. gineering Research Center (Texas Tech University) at the Reese Technology Center. Two antennas, installed c. Landline phone at the 61-m level, serve as the base radio station. A short-haul radio link is used to transfer all data to a data Mesonet stations using landline phone technology collection computer at the WTM facility approximately were not considered given the potential for recurring 3.2 km from the base station. costs and station siting limitations. However, a coop- Each station within the radio communication net- erative effort with the local NWS Office and Southern

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Region Headquarters of the NWS has provided three River Forecast Center in Fort Worth, Texas. As of this landline phone connections as of this writing. One more writing, accessing WTM data through the Web site con- station with a landline phone connection will be con- tinues to be the most popular method for viewing and structed later this year as part of the cooperative effort ingesting data. mentioned above. While 5-min data are available for these WTM stations, the cost of making a connection to b. File Transfer Protocol (FTP) each landline site every 5 min is prohibitive. Therefore, unless there is an active weather situation, the landline File Transfer Protocol was made available to those stations are only called once or twice an hour. users who preferred this method of ingesting data as opposed to the WWW. Several user accounts were set up to meet their needs. These users preferred FTP to d. Microserial server—Internet WWW access because of automation issues such as Other modes of communication are occasionally con- script writing. sidered to improve the WTM communication network with regards to data transfer and to reduce recurring c. Local Data Manager (LDM) costs. One such improvement was to take advantage of ubiquitous Internet connections in/near the WTM do- Unidata’s Local Data Manager is also used to dis- main. In a cooperative effort, a municipality in the tribute WTM data to several universities as well as Texas Panhandle provided an Internet connection free other government agencies. of charge along with tower space on the roof of their building for a radio antenna. A Campbell Scientific 7. Quality assurance NL100 microserial server serves as the mesonet station’s interface to the Internet and a spread-spectrum The current configuration of the WTM produces radio connection provides a link between the microse- 11 520 daily meteorological observations (288 meteoro- rial server and the mesonet station. Polling software on logical observation sets each day from each of the 40 the base station computer then initiates a call to the stations). The large number of observations requires a mesonet station through the Internet and radio link. comprehensive quality assurance/quality control (QA/ Five-min data are available on a real-time basis. QC) procedure to check the quality of the data and The advantages of Internet-based data collection sys- provide necessary advisory information. QA/QC for tem are numerous and might have far reaching effects the WTM is performed in two steps. In the first step, that could determine the future of the WTM. Some predefined tests are applied to the collected data in an advantages are reduction or elimination of recurring effort to highlight or flag suspicious or potentially bad costs, no FCC licensing required for one watt spread- data. In the second step, the flagged data are examined spectrum radio technology, and using an existing net- by a “decision maker” to resolve the legitimacy of the work backbone instead of having to build and/or main- data. Beyond these established QA/QC routines, the tain an associated network backbone. WTM staff provides qualitative checks on all incoming data to identify failing instruments, communication problems, or other issues affecting data quality and 6. Data distribution availability. Once identified, repairs are made as quickly as possible. Another goal of the WTM is to make mesonet data freely and conveniently available to a wide variety of users via the Internet. However, a computer program a. Data had to be created that would ingest, parse, and produce There are two observational groups, agricultural and output in a useable format. Within a few days, the first meteorological. The meteorological parameters are ob- products were made available online to the public on served every 5 min and consist of 15 parameters as the WTM Web site (see below). Archived data are shown in Table 3. Agricultural parameters are observed available upon request. every 15 min and consist of the 10 parameters shown in Table 4. a. World Wide Web (WWW) b. Procedures The first mesonet products appeared on the WTM Web site (http://www.mesonet.ttu.edu) and included The quality of the data is not only a concern for basic climatological information such as high and low researchers, but also real-time users. Since the ma- temperatures for the day, total liquid precipitation, chines perform objectively by nature, QA/QC proce- peak wind speed/direction, etc. Coded meteorological dures become significantly important especially for observations were also made available in METAR and datasets obtained from automated sites. Different types Standard Hydrometeorological Exchange Format of QA/QC tests are proposed and applied in the litera- (SHEF) for regional NWS Offices and the West Gulf ture depending on the kind of network, type of obser-

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TABLE 3. Meteorological parameters recorded using a 5-min Once collected, five distinct tests are applied to de- temporal resolution. termine the quality of each single observation. For each Index Parameter Units test, the observation is flagged with a “0,”“1,”“2,” or Ϫ “3” flag numbers in order to define the confidence level 1 Wind speed scalar (10 m) m s 1 2 Wind speed vector (10 m) m sϪ1 of the observation where “0” indicates “good,” 1 indi- 3 Wind direction (10 m) ° cates “suspect,” 2 indicates “warning,” and 3 indicates 4 Wind direction std dev (10 m) ° “failure.” Each observation is initially assigned with the Ϫ1 5 Wind speed std dev (10 m) m s flag number 0 for each test and flag number for the 6 Wind speed peak gust (10 m) m sϪ1 7 Wind speed (2 m) m sϪ1 corresponding test is updated, if the observation fails. 8 Temperature (1.5 m) °C Each observation is flagged based on the result of the 9 Temperature (9 m) °C range test, step test, persistence test, like instrument 10 Temperature (2 m) °C test and spatial test. The upper/lower limitations and 11 Barometric pressure mb threshold values for each test are predefined by taking 12 Rainfall in. 13 Relative humidity (1.5 m) (%) the meteorological records and instrumentation limita- 14 Dewpoint temperature °C tions (Sonmez and Doggett 2003). The range test is 15 Solar radiation W mϪ2 performed to check if the observation lies between reasonable parameter levels. Any observation outside the reasonable range is flagged as a failure. Unexpected vation, and observed parameters (e.g., Wade 1987; jumps in the data are qualified with the step test. Ad- Meek and Hatfield 1994; Gandin 1988). The QA/QC jacent data points with a difference higher than the tests defined by Shafer et al. (2000) are applied to predefined maximum step allowance are flagged as a WTM datasets in much the same manner as they are warning. applied to the Oklahoma Mesonet (Fiebrich and Craw- The persistence test is used to examine a group of ford 2001). A FORTRAN application was developed to observations within a specific time window. It is useful apply the tests; additional tests and modifications have in locating damaged instruments or those that might be been made for the West Texas territory, which the net- “stuck” at a particular reading. The first step of the test, work serves. Critical data values required for each test the variance test step, compares the variance of the were examined to ensure they were set appropriately dataset contained within the time window with the pre- for West Texas. defined threshold variance. All the observations in the Before applying the QA/QC tests, the raw data for time window are flagged as warning if the estimated each site are separated into monthly agricultural and variance is less than the threshold variance. The data meteorological data files, providing for a convenient are flagged as suspect if they are less than 2 times the file size and naming convention. A standard format is threshold variance. The second step evaluates the maxi- incorporated that includes site ID, the time of the ob- mum difference (difference between maximum and servations, and the parameter values. The gaps in the minimum value of the time window) with the pre- agricultural and meteorological observations are filled defined delta threshold. The observations are flagged with “Ϫ99.99” values to provide consistency in the QA/ as either warning or suspect depending on whether the QC test applications and for the benefit of future users. maximum difference is less than the minimum delta Given the rigorous maintenance schedule, which in- threshold or less than one and one-half times the delta cludes downloading all data from each datalogger, no threshold. The zero test is then applied as the last step data are lost strictly because of communication prob- and captures continuously repeating observational val- lems. Approximately 99.99% of the potential agricul- ues of zero. All of the observations in the time window tural and meteorological parameters are collected. are flagged as warning if the number of recorded zero values exceed 2. The like instrument test is used to compare observa- TABLE 4. Agricultural parameters recorded using a 15-min temporal resolution. tions of like parameters. The test is performed on the temperature observations taken at 2 and 9 m and wind Index Parameter Units speed observations at 2 and 10 m. Temperature obser- 1. Natural soil temperature (5 cm) °C vations are flagged as suspect if the difference between 2. Natural soil temperature (10 cm) °C two parameters is greater than a predefined threshold 3. Natural soil temperature (20 cm) °C 4. Bare soil temperature (5 cm) °C value. On the other hand, observations are flagged as 5. Bare soil temperature (20 cm) °C warning if the difference is greater than 2 times the 6. Soil water content (5 cm) VWC* threshold value. 7. Soil water content (20 cm) VWC* A one-pass Barnes analysis (Barnes 1964) is per- 8. Soil water content (60 cm) VWC* formed for the spatial test to determine the gross errors 9. Soil water content (75 cm) VWC* 10. Leaf wetness unitless in individual observations. For this test, the observations from neighboring sites are used to get an esti- * Volumetric water content. mated observation for a particular site. A standardized

Unauthenticated | Downloaded 10/02/21 01:10 PM UTC 220 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME 22 value is obtained by using the estimated and observed TABLE 6. Percentage of flagged agricultural data by parameter values for the site. The observation is flagged as warn- based on the 2002 dataset. ing if the standardized value is greater than 3, or suspect Parameter Percentage (%) if the standardized value is greater than 2. Natural soil temperature (5 cm) 0.059 All the flag information is accumulated in an output Natural soil temperature (10 cm) 0.058 file for the decision maker and prospective users of the Natural soil temperature (20 cm) 0.135 dataset. At this point, the flag information and raw and Bare soil temperature (5 cm) 0.035 corrected data files are kept completely separate, but a Bare soil temperature (20 cm) 0.031 Soil water content (5 cm) 0.000 database combining the information is planned for the Soil water content (20 cm) 0.006 future. The flagged percentages of all meteorological Soil water content (60 cm) 0.140 and agricultural parameters based on the 2002 dataset Soil water content (75 cm) 0.124 (representative of 34 stations) are presented in Tables 5 Leaf wetness 0.000 and 6.

of a rapidly evolving severe weather event. Addition- 8. Case study/example ally, the mesonet observations provided a good source The WTM observed a high wind event on 15 April of near real-time warning verification for the local 2003. This significant wind event resulted in an out- NWS Office. On this day the WTM observed 16 severe Ն Ϫ1 break of severe weather, including 11 tornado reports wind reports 50 kt (25.7 m s ) over the South Plains. in West Texas and southwest Oklahoma, and a blinding In addition to providing greatly improved resolution dust storm in southeast New Mexico and West Texas. (both temporal and spatial) in the surface observations, The storm was a product of a dynamic upper-level low the WTM also possesses a sounding system that was ejecting rapidly from the desert southwest into the utilized during this event. Two soundings, launched at Southern High Plains. The progression of the upper- 1500 and 1800 UTC from Reese Center, were made level low resulted in rapid surface cyclogenesis in south- readily available on the Internet. Additionally, the east Colorado with a well-defined dryline setup south soundings were passed directly to the NWS. Figure 7 through West Texas. The dryline acted as a trigger for presents the 1800 UTC sounding. The sounding was the initiation of a number of discrete supercells and released approximately four hours before the dryline subsequently aided in the formation of a squall line in passed through Reese Center and indicates strong Ͼ the moist air east of its position. Following the dryline south-southwest winds at the surface veering to 100 passage, winds quickly shifted to the southwest, usher- ing in much drier air and dust. Figure 6 displays the surface wind speed and direction throughout the WTM domain at 1730 LST. The figure shows strong south winds present in the southeast counties with winds rapidly shifting to the southwest behind the dryline in the central and western counties. The WTM observations allowed forecasters access to timely information, thus enhancing the understanding

TABLE 5. Percentage of flagged meteorological data by parameter based on the 2002 dataset. Parameter Percentage (%) Wind speed scalar (10 m) 0.083 Wind speed vector (10 m) 0.082 Wind direction (10 m) 0.071 Wind direction std dev (10 m) 0.372 Wind speed std dev (10m) 0.170 Wind speed peak gust (10 m) 0.167 Temperature (1.5 m) 0.003 Temperature (9 m) 0.010 Temperature (2 m) 0.009 Relative humidity (1.5 m) 0.652 Barometric pressure 0.020 Rainfall 0.000 Dewpoint temperature 0.004 FIG. 6. Wind speed and direction for the West Texas Mesonet at Wind speed (2 m) 0.608 Ϫ 1730 LST 15 Apr 2003. One full barb represents5ms 1 and a flag Solar radiation 0.002 Ϫ represents 25 m s 1.

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FIG. 7. Sounding launched from Reese Center at 1800 UTC 15 Apr 2003. The temperature (solid line) and dewpoint (dashed line) are in degrees Celsius. The wind speed is in knots. kt (51.4 m sϪ1) west-southwest winds aloft. The sound- 15-min agricultural data are also collected and relayed. ing also depicts a weakly capped atmosphere with mar- All real-time data are available and archived data can ginal CAPE (394 J kgϪ1). Placing this vertical wind be requested. Data are distributed through a variety of profile over the more moist south-southeast wind methods includes WWW, FTP, and LDM. Quality con- present in the eastern counties suggests the increased trol and assurance procedures have been developed. likelihood for the formation of severe convection, in- Questionable and/or bad data are automatically flagged cluding the development of supercells capable of pro- through a set of FORTRAN routines, while a human ducing tornadoes. decision maker renders a final conclusion. A Web in- Therefore, in this case, the presence of the WTM terface to enable access to the archived dataset is cur- aided in more accurately identifying the existence, lo- rently under development. cation, and evolution of the dryline as it translated through West Texas. It also provided a timely, accurate, Acknowledgments. The WTM was funded by a grant and efficient platform for NWS to verify severe thun- from the Texas Department of Economic Development derstorm and high wind warnings. (TDED). Additional support has been provided by the Wind Science and Engineering Research Center and Geosciences Department at Texas Tech University, 9. Summary and NIST (Department of Commerce NIST/TTU Co- operative Agreement Award 70NANB8H0059). This The WTM now maintains 40 surface stations located project would not be possible without the support of over western Texas. Each station observes and relays the local county judges, city officials, and private citi- (via radio, cell or land phone, or through an Internet zens who graciously allow us the use of their land to connection) real-time (5-min) meteorological data back install mesonet stations free of charge. The authors to Reese Technology Center in Lubbock, Texas, the thank Jeff Walsh and Mark Conder for developing base for the project. In addition to meteorological data, some of the schematics and diagrams used within this

Unauthenticated | Downloaded 10/02/21 01:10 PM UTC 222 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME 22 article. The authors thank three anonymous reviewers Meek, D. W., and J. L. Hatfield, 1994: Data quality checking for who provided valuable input to improve this paper. single station meteorological databases. Agric. For. Meteor., 69, 85–109. Richardson, S. J., 1995: Multiplate radiation shields: Investigating REFERENCES radiational heating errors. Ph.D. dissertation, University of Oklahoma, 134 pp. [Available from 100 E. Boyd, Suite 1210, Barnes, S. L., 1964: A technique for maximizing details in numeri- Norman, OK 73019.] cal weather map analysis. J. Appl. Meteor., 3, 396–409. Brock, F. V., K. C. Crawford, R. L. Elliott, G. W. Cuperus, S. J. Shafer, M. A., T. Hughes, and J. D. Carlson, 1993: The Oklahoma Eighth Symp. Stadler, H. L. Johnson, and M. D. Eilts, 1995: The Oklahoma mesonet: Site selection and layout. Preprints, on Meteorological Observations and Instrumentation, mesonet: A technical overview. J. Atmos. Oceanic Technol., Ana- heim, CA, Amer. Meteor. Soc., 231–236. 12, 5–19. Brotzge, J. A., and K. C. Crawford, 2000: Estimating sensible heat ——, C. A. Fiebrich, D. S. Arndt, S. E. Fredrickson, and T. W. flux from the Oklahoma Mesonet. J. Appl. Meteor., 39, 102– Hughes, 2000: Quality assurance procedures in the Oklaho- 116. ma Mesonetwork. J. Atmos. Oceanic Technol., 17, 474–494. Fiebrich, C. A., and K. C. Crawford, 2001: The impact of unique Sonmez, I., and A. L. Doggett, 2003: The West Texas data archive: meteorological phenomena detected by the Oklahoma Me- A tool for wind science and engineering research in West sonet and the ARS Micronet on automated quality control. Texas. Proc. 11th Int. Conf. on Wind Engineering, Lubbock, Bull. Amer. Meteor. Soc., 82, 2173–2187. TX, ICWE/NIST, 2021–2028. Gandin, L. S., 1988: Complex quality control of meteorological Wade, C. G., 1987: A quality control program for surface meso- observations. Mon. Wea. Rev., 116, 1137–1156. meteorological data. J. Atmos. Oceanic Technol., 4, 435–453. Gillespie, T. J., and G. E. Kidd, 1978: Sensing duration of leaf World Meteorological Organization, 1983: Guide to Meteorologi- moisture retention using electrical impedance grids. Can. J. cal Instruments and Methods of Observation. 5th ed. World Plant Sci., 58, 179–187. Meteorological Organization, 483 pp.

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