|Van Vactor, Steven|
|Van Liew, Michael|
Submitted to: Interagency Conference on Research in the Watersheds
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2003
Publication Date: October 20, 2003
Citation: Hardegree, S.P., Van Vactor, S.S., Healy, K.R., Alonso, C.V., Bonta, J.V., Bosch, D.D., Fisher, D.S., Goodrich, D.C., Harmel, R.D., Steiner, J.L., Van Liew, M.W., 2003. Multi-watershed evaluation of WSR-88D (NEXRAD) radar-precipitation products. In: Proceedings of the First Interagency Conference on Research in the Watersheds, October 28-30, 2003, Benson, Arizona, p. 486-491. Interpretive Summary: The National Weather Service operates 160 NEXRAD radar systems to measure hazardous weather conditions over most of the lower 48 United States. Although these sites were installed to monitor hazardous weather, they also estimate precipitation every hour over a 4 km grid that covers over 90% of these States. Our purpose was to use rainfall data from the ARS watershed network to determine whether these precipitation data were of sufficient accuracy to be used in other hydrologic and natural resources modeling applications. We used over 150 rain gauges in 6 ARS watersheds and compared radar and gauge estimates using 3 years of data. In 5 of 6 cases, the radar underestimated ground precipitation and in all cases, the gauge network detected precipitation during a much larger number of hours than was the case with the radar. Modification of NWS precipitation and processing protocols might improve the accessibility and utility of these data for hydrologic and natural-resource modeling applications.
Technical Abstract: The National Weather Service (NWS) operates a network of Doppler-radar stations (NEXRAD, WSR-88D) that produce hourly-rainfall estimates, at approximately 4-km resolution, with nominal coverage of 96% of the conterminous US. Utilization of these data by the NWS are primarily for the detection and modeling of extreme-weather events. Radar-precipitation estimates were compared with gauge estimates at 6 ARS watershed-research locations in Idaho, Arizona, Oklahoma, Georgia and Mississippi, to evaluate the utility of these data for hydrologic and natural resources modeling applications. Radar precipitation estimates underestimated gauge readings for all locations except Tucson. In all cases, the total number of hours with measured-radar precipitation was much less than hours containing gauge-precipitation estimates. Additional modification of NWS precipitation processing procedures will be necessary to improve accessibility and utility of these data for hydrologic and natural resource modeling applications.