NCAR/TN-237+IA NCAR TECHNICAL NOTE II - I I I - - I - II - I II II- I II --- II I -I - - June 1984 Instructor's Handbook on Meteorological Instrumentation Fred V. Brock, Editor Carol E. Nicolaidis, Assistant Editor ATMOSPHERIC TECHNOLOGY DIVISION -I I -··~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~e - --I NATIONAL CENTER FOR ATMOSPHERIC RESEARCH BOULDER, COLORADO iii CONTRIBUTORS C. Bruce Baker University of Michigan William Bradley Oregon State University Fred Brock National Center for Atmospheric Research Harold Cole National Center for Atmospheric Research Ulrich Czapski State University of New York at Albany Anders Daniels University of Hawaii at Manoa Russell Dickerson University of Maryland Don Dickson University of Utah Claude E. Duchon University of Oklahoma C. W. Fairall Pennsylvania State University L. Keith Hendrie Illinois Dept. of Energy and Natural Resources John H. Hirsch South Dakota School of Mines and Technology George L. Huebner Texas A&M University James F. Kimpel University of Oklahoma Warren W. Knapp Cornell University G. Garland Lala New York Atmospheric Sciences Research Center Albert J. Pallmann St. Louis University Julian Pike National Center for Atmospheric Research Hans Richner Laboratory for Atmospheric Physics of the Swiss Federal Institute of Technology William Shaw Naval Postgraduate School John T. Snow Purdue University Steve Stage Florida State University Alfred Stamm State University of New York at Oswego Eugene S. Takle Iowa State University Dennis W. Thomson Pennsylvania State University PREFACE The objective in preparing this Instructor's Handbook is to pro- vide useful material to assist instructors in teaching meteorological instrumentation. It is intended to provide flexibility in meeting the needs of individual teaching programs. The Handbook, therefore, pro- vides a variety of teaching materials: text, references, questions, problems, and laboratory exercises. Its purpose is to fill the existing gap in meteorological teaching texts, until better textbooks become avai 1able. An instructor using this Handbook faces two problems: 1) how to get the material to the students, and 2) how to adapt it to a specific program. These problems were taken into consideration and solved by not copyrighting the Handbook and producing it in a loose leaf, three- hole-punched form. It may be personally copied and distributed for only the cost of reproduction. The instructors may either delete or add relevant material to obtain their personal program plan. The history of the ATD Colloquium on the Teaching of Meteorologi- cal Instrumentation is exemplified in Chapter 1 by James F. Kimpel. The colloquium received the full endorsement of the University Corpora- tion of Atmospheric Research (UCAR), the National Center for Atmo- spheric Research (NCAR), the National Science Foundation (NSF), and the Board of Meteorological and Oceanographic Education in the Universities of the American Meteorological Society. In behalf of the participants, I would like to thank Wilmot Hess, Director of NCAR, and Robert Serafin, Director of NCAR's Atmospheric Technology Division, for their assistance and support. I would also like to thank the participating universities for providing support to their faculty members who attended. In addition, the contributors deserve the highest praise for their diligence and their very fine contributions. Special thanks go to the following NCAR staff. Harold Cole and Julian Pike assisted greatly in the preparation and presentation of lectures for the colloquium. Tony Darnell assisted in preparing materials. Diane Wilson made all local arrangements. The assistant Editor, Carol Nicolaidis, coordinated and supervised the process of getting the diverse contributions into a coherent form. This was a difficult and challenging task and she did a splendid job. -, °7V.rCE . ......, Fred V. Brock, Editor 30 May 1984 v TABLE OF CONTENTS CONTRIBUTORS ......................... iii PREFACE ............................ iv TABLE OF CONTENTS . ...... v LIST OF FIGURES ....... ix LIST OF TABLES ..................... xi CHAPTER 1 Introduction 1.0 Statement of the Problem ........ ...... 1-1 1.1 Background . ...... 1-2 1.2 The 1983 ATD Colloquium on the Teaching of Meteorological Instrumentation . ............... .. 1-3 1.3 Organization of the Instructor's Manual ....... 1-4 1.4 References ....................... 1-5 CHAPTER 2 Performance Characteristics of Sensors 2.0 Introduction ............. .. ..... 2-1 2.0.1 Performance Characteristics: Input/Output (I/O) . 2-1 2.0.2 Static Vs Dynamic Characteristics ........... 2-1 2.0.3 Objective of Chapter . 2-2 2.0.4 Complexity of Defining Terms . 2-2 2.1 Static Characteristics ....... ........ 2-3 2.1.1 Detailed Definition of a Static Characteristic . .. 2-3 2.1.2 Concept of an I/O Diagram ............... 2-3 2.1.3 Definition of Terms ............. .. 2-5 2.1.4 Comments of the Relative Importance of Static Response Characteristics ................... 2-10 2.1.5 Questions, Problems, and Laboratory Exercises ..... 2-10 2.2 Dynamic Characteristics . ........... ... 2-14 2.2.1 Physical Systems and Mathematical Models ...... 2-14 2.2.2 First-Order Systems .................. 2-16 2.2.3 Second-Order Systems ................. 2-36 2.2.4 Example of a First-Order System ............ 2-54 2.2.5 Need for Higher Order and Nonlinear Models ....... 2-57 2.2.6 Questions, Problems, and Laboratory Exercises .. .. 2-66 2.3 References . 2-68 2.4 Bibliographic Information ............... 2-68 vi TABLE OF CONTENTS CHAPTER 3 Calibration Standards 3.0 Introduction . o . .O O e . * 0 o 0 0 9 3-1 3.1 Standards Authorities . o . e . o 00 e 0 a 3-3 3.2 Types of Standards . o ·· 0 3-4 3.3 Standards for Fundamental Meteorological Variables 0 3-5 3.3.1 Pressure .. .. 0 0 0 0 * s · O · 0 3-5 0 3.3.2 Temperature ........ 0 0 9 0 0 *00* 3-6 0 3.3.3 Wind Speed ......... 0 0 * * * * 3-7 0 0 0 0 3.3.4 Humidity .. ..... 0 0 0 0 * * * 3-8 0 0 3.3.5 Radiation ......... 0 0 * * * 0 3-8 0 0 0 3.4 Other Standards Laboratories 0 0 * * * * 0 0 3-9 0 0 3.4.1 Noncommercial Laboratories 0 0 * * · 3-9 0 0 3.4.2 Commercial Laboratories 0 0 * **·· 0 3-9 a 0 3.5 Questions and Problems . 0 0 o e e · 3-10 0 0 3.6 References ......... 0 0 o o o 3-13 0 0 0 3.7 Bibliographic Information 0 0 · *· · 0 0 3-14 CHAPTER 4 Measuring Devices 0 9 4.0 Introduction ......... * * O * * * O O ® 0 0 4-1 4.1 Temperature ......... 0 0 4-2 4.1.1 Introduction ... o.. a 0 4-2 4.1.2 Required Background . .. 0 4-3 4.1.3 Temperature Sensors . .. 0 4-3 4-19 4.1.4 Temperature Measuring Problems inAir i .....0 8 4.1.5 Questions and Problems .. 4-19 · o e oc · · · 4.2 Humidity ........... * · · · · 4-21 8 v v · v 0 4.2.1 Background .......... · · 0 ® ·8 · · e 4-21 0 @ o 0 s 0 4.2.2 Sensor Physical Principles a 4-22 0 0 0 0 e 'o 4.2.3 Sensor Descriptions . .. 0 4-23 4.2.4 Applications . ....... 0 4-24 4.2.5 Questions, Problems, and Laboratory Exercises 0 0 4-26 0 4.3 Wind . .. 0 0 4-31 4.3.1 Required Background ............ 0 4-31 4.3.2 Theoretical Background ............ 0 4-31 4.3.3 Description and Calibration of Sensors . 0 4-42 4.3.4 Application of Sensors .. ... 0 0f 4-50 4.3.5 Questions, Problems, and Laboratory Exercises 4-55 4.4 Pressure . .................. 4-71 4.4.1 Prerequisites . .* .. * .* .* 0 0 4-71 4.4.2 Theoretical Considerations and Rationale o . 0 4-71 4.4.3 Laboratory Exercises .... 0 4-82 4.5 Radiation ... ............... 0 0 4-93 4.5.1 Required Background ...... *.*.. 4-93 4.5.2 Radiation Transducers and Sensors ...... G 4-100 4.5.3 Applications ................. 4-103 4.5.4 Questions and Laboratory Exercies ...... 4-107 vii TABLE OF CONTENTS 4.6 Precipitation ..................... 4-122 4.6.1 Introduction ...... 4-122 4.6.2 Theoretical Background for Precipitation Instrumentation 4-123 4.6.3 Description and Calibration of Precipitation Instrumentation . .. .. .. 4-126 4.6.4 Applications .......... ........... 4-132 4.6.5 Questions, Problems, and Laboratory Exercises . ... 4-135 4.7 Evaporation ...... .............. .4-141 4.7.1 Required Background ........ 4-141 4.7.2 Theoretical Background . ...... 4-141 4.7.3 Nature of Variables and Purpose of Measurements .... 4-144 4.7.4 Direct Measurement Devices ... ... .. 4-145 4.7.5 Questions and Laboratory Exercise ... 4-146 4.8 References . .............. .... 4-147 4.9 Bibliographic Information ............... 4-156 CHAPTER 5 Field Environment 5.0 Introduction .... .... .... .. .....5-1 5.1 Atmospheric Exposure .................. 5-1 5.1.1 Temperature and Humidity Sensor Exposure ....... 5-1 5.1.2 Anemometer Exposure . .. 5-2 5.1.3 Precipitation Sensor Exposure ............. 5-3 5.1.4 Radiation Instrument Exposure . 5-4 5.1.5 Pressure Sensor Exposure . .. 5-4 5.1.6 Questions and Laboratory Exercises ......... .5-5 5.2 Instrumentation Support Systems: Platforms, Towers, Aircraft Sondes ................... 5-6 5.2.1 Background ................... ... 5-6 5.2.2 Types of Support Systems ........... .. .. 5-6 5.2.3 Application of Support Systems ............. 5-7 5.2.4 Towers . 5-8 5.2.5 Other Instrument Support Structures ......... 5-13 5.2.6 Questions and Problems ......... ....... 5-16 5.3 Data Quality Assurance ................. 518 5.3.1 Background ...................... 5-18 5.3.2 Field Intercomparisons ................. 5-18 5.3.3 Quality Assurance Plans .............. 5-19 5.4 Real-Time Analysis . 5-23 5.4.1 Purpose . 5-23 5.4.2 Examples of Real-Time Analysis . ....... 5-23 5.4.3 Display Methods . 5-23 5.4.4 Practical Considerations . ............ 5-24 5.5 References . 5-25 viii TABLE OF CONTENTS CHAPTER 6 Meteorological Measurement Systems 6.0 Introduction .