Zhang - Weather radar polarimetry

Weather Radar Polarimetry

Weather Radar Polarimetry

Guifu Zhang

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Library of Congress Cataloging-in-Publication Data

Names: Zhang, Guifu, 1962

Title: Weather radar polarimetry.

Description: Boca Raton : Taylor & Francis, 2016. | A CRC title. | Includes bibliographical references and index.

Identifiers: LCCN 2016005615 | ISBN 9781439869581 (alk. paper)

Subjects: LCSH: Radar meteorology. | Polarimetry. | Radar--Interference. | Electromagnetic waves--Scattering. | Remote sensing.

Classification: LCC QC973.5 .Z43 2016 | DDC 551.63/53--dc23

LC record available at http://lccn.loc.gov/2016005615

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Contents

Although weather radars have been in operation for more than half a century and Doppler weather radars for a few decades, polarimetric weather radars, which retain Doppler capability, have only recently achieved operational status. Nevertheless, polarimetry offers more than an incremental improvement in the understanding of cloud physics, in quantitative measurements of precipitation, and in the discrimination of scatterer types. In fact polarimetric weather radars are likely to have a broader impact on improving the interpretation and quantitative measurement of weather phenomena than that achieved with Doppler radars. Thus users of polarimetric radar need to understand the basics of polarimetry so they can better interpret the data provided by this instrument. There are several texts describing the theory and application of weather radars including Doppler radars, but relatively few that focus on polarimetry. At the University of Oklahoma, Dr. Guifu Zhang created a popular course containing the theory and application of polarimetry to interpret polarimetric radar echoes from various types of precipitation as well as those from biological scatterers. Weather Radar Polarimetry is rooted in this course, offered to students in the School of Meteorology as well as those in the School of Electrical and Computer Engineering. Thus this book has benefited from the interactions of Dr. Zhang with students from two disciplines, as well as from his collaboration with researchers at the National Center for Atmospheric Research and the National Oceanic and Atmospheric Administrations National Severe Storms Laboratory. In Weather Radar Polarimetry Dr. Zhang takes a unique approach to teaching weather echo processing, polarimetric theory, and the application of theory to the interpretation of polarimetric weather radar observations. Homework assignments and examples with real data offer hands-on experience and demystify this difficult subject. Those who put the time into working out the details will be well prepared to enter this field either as developers of polarimetric radars or interpreters of polarimetric data.

Richard J. Doviak
Dusan S. Zrni
National Severe Storms Laboratory
National Oceanic and Atmospheric Administration

Radar has proven to be an indispensable tool for weather studies, as has been well documented. Radar reflectivity and Doppler measurements have demonstrated their value in weather observation, quantification, and forecasting. Now, we have another set of measurements we can use to better study weather: polarimetric radar data (PRD). After decades of research and development, weather radar polarimetry has now matured to the point that the national NEXRAD (WSR-88D) network has been upgraded with dual-polarization capability. Furthermore, other national weather radar networks have radars capable of producing multiparameter PRD. My understanding of weather radar polarimetry is as follows:

There is polarimetry in radar innovation,

which makes weather observations more accurate.

It brought excitement with hydrometeor classification,

and improvement in quantitative precipitation estimation.

Multiparameter measurements contain rich information,

leading to a deeper understanding of cloud physics.

It helps model initialization and parameterization,

with great potential for the future of weather prediction!

Although the technology of radar polarimetry has matured and PRD are available nationally and worldwide, radar polarimetry is still in its initial stages for operational usage. There is a lot of room for research and development, especially in using PRD for weather forecasts. It is important to know the principles of radar polarimetry and of PRD estimation and improvement, as well as information content, and error characterization. There is a growing need for a textbook that meteorology students, scholars, and scientists can use to obtain this knowledge. Based on the weather radar polarimetry classes taught by the author at the University of Oklahoma, this book was written to provide readers with the fundamentals and tools to effectively and optimally use the available PRD. Please find supporting data and tools for the homework exercises at http://weather.ou.edu/~guzhang/page/book.html.