A National Vision for the Use of Spatially Distributed Precipitation Data

Featuring David C. Curtis, Ph.D.
Vice President, Business Development
Carlton Engineering

Location:  2430 Engineering Hall
Free and open to the public

Abstract:
Since the early 1990’s when the National Weather Service began deployment of the WSR-88D weather radars, the use of radar rainfall estimates in water resources applications has increased dramatically.
Nearly 15 years of WSR-88D radar rainfall estimates are now available in most areas of the United States.
Radar-rainfall estimates, when combined with rain gage observations, provide an improved understanding of the spatial variability of rainfall. Spatial resolutions on the order of 1 km x 1 km in 5 minute time steps are commonly available. Higher resolutions of 0.25 km x 0.25 km and 1 minute time steps are now available in some areas.

When matched with hydrologic models of similar spatial resolution, typically GIS-based, incredibly detailed analyses are possible. Hydrologic features, especially in fast responding watersheds or individual urban neighborhoods, can now be resolved.

While hydrologic simulations dominate current water resources applications using radar rainfall estimates, new applications for spatially distributed precipitation data sets are emerging. For example, recent investigation explored the use of radar rainfall in forecasting the spatial distribution plant disease risk. Radar rainfall estimates are also used in density distribution assessments for a variety of plant and animal ecosystems.

The growing national data base of spatially distributed radar rainfall data offers an incredibly rich opportunity to mine information about the detailed structure of storms and local climate. Nationally, nearly every hydrologic design standard has been derived from point rain gage data and each suffers from all the biases associated with extending point rainfall estimation to areal process. New insights gained from analyzing high resolution radar rainfall on a large scale over an extended time, have the ability to significantly impact all current hydrologic design standards affecting trillions of dollars of constructed facilities.

In many respects WSR-88D radars are to hydrologists what the Hubble telescope has been to astronomers. Before Hubble, astronomers were beginning to believe that they knew everything there was to know about the universe. Looking deep into our past, Hubble discoveries continue to astonish and surprise. Peering into the heart of storms, WSR-88D radars do the same for water resource scientists and engineers.

This presentation will review advances in national radar rainfall data sets through the last decade, identify some of the critical issues facing radar rainfall analysts, discuss emerging applications for spatially distributed rainfall, and discuss implications of radar rainfall data sets in hydrologic design.