Doppler radars are now considered to be an indispensable tool in the measurement and forecasting of atmospheric phenomena. The deployment of WSR–88D radars, the terminal Doppler weather radar (TDWR) at major airports, and wind-profiling radars in the USA can all be considered as major milestones in the operational application of the Doppler principle. Another milestone is the successful deployment of the first precipitation radar in space as part of the Tropical Rainfall Measurement Mission (TRMM). Measurement of the reflectivity and velocity of precipitation particles basically exploits the information contained in the amplitude and phase of the scattered electromagnetic wave. In the last two or three decades, it has become increasingly clear that significant information is also contained in the polarization state of the scattered wave. The physical and experimental basis for the application of radar polarimetry to the study of precipitation is the main subject of this book.

The evaluation of polarimetric measurement options for operational WSR–88D radars is gaining momentum and, if realized, will result in widespread application of polarimetric techniques by a broad segment of the meteorological community. Basic and applied research in polarimetric radar meteorology continues to be strong world-wide, especially in Europe and Japan. We believe that the time has arrived for a detailed treatment of the physical principles underlying coherent polarimetric radar for meteorological applications.

This book is based in part on a graduate class taught by the authors at Colorado State University since the mid-1980s.