Radar for meteorologists or you, too, can be a radar meteorologist.

352 Pages·1991·17.357 MB·English

by  Rinehart, Ronald E.

Radar for
Meteorologists
or
You, too, can be a Radar
Meteorologist,
Part III
Second Edition
by
Ronald E. Rinehart
Department of Atmospheric Sciences
Center for Aerospace Sciences
University of North Dakota
Grand Forks, North Dakota 58202-9006
United States of America
To Linda
Front Cover: Freezing rain storm detected by the UND C-band weather
radar while operating in Kansas City, Missouri, on 14 February 1990.
The left side shows Doppler radial velocity while the right side shows
radar reflectivity factor. Elevation angle = 6.5°.
Back Cover: Range Height Indicator display of the same storm as on the
front cover. Velocity data are the top panel while reflectivity data are the
bottom panel. See ’’General Comments" in Color Figure section for
information on interpreting the figures.
Cover designed by Chuck Crummy.
Printed by Knight Printing Company, Fargo, North Dakota
Third printing: May 1994
Copyright © 1991 by Ronald E. Rinehart
ISBN 0-9608700-7-5
Available from:
Radar for Meteorologists
P.O. Box 6124
Grand Forks, ND 58206-6124
United States of America
701-772-7647
fax: [phone]
Table of Contents
Preface vii
Preface to the Second Edition xii
List of Figures xiii
List of Tables xiv
Chapter 1: Introduction 1
History of radar 4
Types of radar 7
Chapter 2: Radar hardware 11
Transmitter 11
Antenna 14
Waveguide 21
Transmit/Receive Switch 22
Receiver 23
Displays 24
Chapter 3: Electromagnetic waves 33
Chapter 4: Radar equation for point targets 47
Chapter 5: Distributed targets 59
Chapter 6: Doppler velocity measurements 73
Chapter 7: Spectrum width and turbulence 97
Chapter 8: Non-meteorological targets 103
Point targets 103
Standard targets 103
Birds 106
Aircraft 107
Distributed point targets 109
Ground targets 109
Insects 110
Table of Contents
Chapter 9: Meteorological targets 113
Clouds 113
Rain 116
Raindrop size distributions 117
Z-R relationships 119
DVIP levels 120
Snow 121
Bright band 123
Hail 127
Attenuation 129
Atmospheric attenuation 130
Cloud attenuation 132
Rain attenuation 135
Snow attenuation 135
Hail attenuation 137
Recognizing the presence of attenuation 138
Other meteorological targets 139
Chapter 10: Clear-air return 141
Sources 141
Particulates 142
Refractive index gradients 147
Detectable wind phenomena 149
Winds 149
Gust fronts 155
Turbulence 161
Clutter 162
Chapter 11: Advanced meteorological uses of radar 165
Rainfall measurements 165
Dual-wavelength radar 168
Polarization diversity 171
Circular depolarization ratio 172
Dual-Doppler processing 175
Chapter 12: NEXRAD and TDWR 181
Next Generation Radar (NEXRAD, WSR88-D) 181
Terminal Doppler Weather Radar (TDWR) 185
IV
Table of Contents
Chapter 13: Quantification 189
Directional couplers 190
Transmitter power 191
Transmitter frequency 194
Received power 195
Receiver bandwidth 205
Pulse duration 206
Antenna gain 207
Antenna beam pattern 218
Antenna beamwidth 219
Range 220
Azimuth and elevation angles 223
Doppler velocity 224
Color Figures 227
General comments 227
Appendix A: Logarithmic units 249
Life on a Logarithmic Scale: 256
Appendix B: Error analysis 261
Appendix C: Tools and toys 281
Appendix D: Specifications and Zmin for selected radars 290
Appendix E: Characteristics of air-traffic control radars 293
Glossary 295
Constants and Conversion Factors 322
References 323
Index 329

Preface
Since the "good old days" when radar was first used to
detect storms until now, radar has changed from a research
tool used only by a few specialists to a tool used by many
people on a daily basis. This transformation from an exotic
and expensive research tool into a basic source of information
for the masses has occurred for several reasons. One is
simply the relative proliferation of radars across the country.
Another is in the ability to communicate the data from place
to place. Still another is that the information provided by
radar is simply so useful that it is foolish not to use it for
many people.
As the field of radar meteorology changed over the
years, so, too, has the typical radar meteorologist. Based on
photographs from some of the early radar conferences and
actual observations of real, live radar meteorologists
presenting papers at a number of radar conferences, I have
watched the changes that have taken place over the years.
Figure 1, first presented at the 22nd Conference on Radar
Meteorology at Zurich, Switzerland (Rinehart, 1984), shows
what the well-dressed radar meteorologist looked like over the
years. Based on a quantitative analysis (least squares linear
regression) on the amount of clothing and facial hair as a
function of time, I was able to forecast what the well-dressed
radar meteorologist of 2006 AD would look like. This
forecast is shown in Fig. 2.
There is a vast and rich number of publications in the
field of radar meteorology. Much of this literature results
Preface
Figure 1 What the well-dressed radar meteorologist
wore in various years.
Figure 2 Forecast of what a radar meteorologist in the
year 2006 AD will look like.
Preface
from specific research studies into the use of radar and its
application to various meteorological problems. Indeed, the
majority of the publications related to radar meteorology are
the results of research performed by hundreds of radar
meteorologists over the past 40 years.
Much of the weather radar research results is found in
the preprint volumes of the 24 conferences on radar
meteorology that have been held since 1947; however, only
the last 23 of these had conference proceedings. From time
to time there have been additional summaries of the current
state of the art. These include an early article in the
Compendium of Meteorology (1952) and the recently published
volume Radar in Meteorology (Atlas, 1990), both of which
were published by the American Meteorological Society.
Another would be the Advances in Radar Meteorology by
Atlas in 1964.
In addition to the refereed literature, the Radar
Conference Preprint volumes, and the special summary
volumes, there have been a, number of textbooks published by
scientists and engineers for scientists and engineers. These
include (roughly chronologically) Rattan’s 1959 Radar
Meteorology and his 1973 revision Radar Observation of the
Atmosphere', Skolnik’s 1970 Radar Handbook and his 1980
Introduction to Radar Systems', Gossard and Strauch’s 1983
Radar Observation of the Clear Air; and Doviak and Zrnic’s
1984 Doppler Radar and Weather Observations. Obviously,
there is a lot of information available in the field of radar
meteorology.
So, why should there be another text on the subject?
Much of the textual material now available is aimed at the
research community with little practical information aimed at
the real users — front line meteorologists. My purpose in
writing this text is to try to fill the gap between the
instruction manual of a radar system and the theoretical