Hydrologic Performance of Rainfall Estimates from Polarimetric Radar

This study presents an analysis of hydrologic simulations performed for a dataset of several rainfall-runoff events, including a 100-year event, that were captured by the polarimetric prototype of the WSR-88D, KOUN. The focus basin is the heavily instrumented Ft. Cobb basin in Oklahoma which features a Micronet, a network of 15 stations that measure air temperature, rainfall, relative humidity, solar radiation, soil temperature at four depths, and soil water content at three depths. The high-density rain gauge network is used to evaluate the polarimetric rainfall algorithms.

We also set up and rigorously calibrated the National Weather Service Office of Hydrologic Development's 19-parameter distributed hydrologic model over a 3-year period. Benchmark simulations are produced from rainfall algorithms using the standard WSR-88D reflectivity-to-rainfall (Z-R) relation as well as a rain gauge-only product, all of which are compared to observed streamflow at three USGS stations situated in the basin. The hydrologic model is then forced with recently proposed rainfall algorithms based on polarimetric variables. Ultimately, we hope to answer: “What will polarimetric radar do for flash flood prediction?”