Radar Hydrology: Principles, Models, and Applications

Book Preface

The origins of radar date back to World War II, when they provided a new and unique capability to detect enemy aircraft, submarines on the ocean surface, and ships. Radar not only changed the face of the war, but once it became adapted to observe the weather, it led to a revolution in meteorology. It has been instrumental in the study of severe thunderstorms, identification of rotation associated with mesocyclones and tornadoes, detection of severe hail and damaging winds, and estimation of heavy rainfall associated with flash floods. For these reasons, many countries throughout the world have invested in large radar networks for routine observations used to warn the public of these imminent weather hazards.

This book focuses on the use of radars in hydrology. Weather radars have proven their value for remote sensing of precipitation, even at high enough resolution to monitor and predict the onset of flash floods. But the process to arrive at an accurate estimate of precipitation from the raw radar signal is not a straightforward one. For this reason, five chapters of this book are dedicated to radar-based precipitation estimation alone. Graduate students, operational forecasters, and researchers will acquire the theoretical framework and practical experience behind radar precipitation estimation.

We present new radar technologies that will improve the accuracy and resolution of precipitation estimates. The description of these platforms, some of which are mobile or transportable, does not attempt to comprehensively cover all new radar technologies. Rather, we focus on platforms that are more familiar to the authors. Likewise, several of the studies we highlight reflect our own experiences with those observing platforms, basins, and methodologies. We supply complete bibliographies and encourage the interested reader to explore those other studies to gain a more holistic understanding of the topics presented herein.

We believe the next revolution in hydrology will be initiated by radar remote sensing of additional variables going beyond precipitation. Space-based, airborne, and ground-based radars operating at multiple frequencies can be used to detect and measure surface water spatial extent and depth, stream discharge, near-surface soil moisture, subsurface water, and depth to the water table. Radars are now providing insights into water storage and fluxes in regions that have only scarcely been observed. These new observations will influence new hydrologic theories, formulations, and basic understanding. Moreover, accurate estimation of the freshwater storage on Earth will provide the pulse of the planet’s climate state.