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SUB-PIXEL RAINFALL VARIABILITY AND THE IMPLICATIONS FOR UNCERTAINTIES IN RADAR RAINFALL ESTIMATES
Citation:
ZHANG, Y., T. ADAMS, AND J. V. BONTA. SUB-PIXEL RAINFALL VARIABILITY AND THE IMPLICATIONS FOR UNCERTAINTIES IN RADAR RAINFALL ESTIMATES. Presented at American Geophysical Union Conference, San Francisco, CA, December 05 - 09, 2005.
Impact/Purpose:
To inform the public.
Description:
Radar estimates of rainfall are subject to significant measurement uncertainty. Typically, uncertainties are measured by the discrepancies between real rainfall estimates based on radar reflectivity and point rainfall records of rain gauges. This study investigates how the discrepancies can potentially arise owing to the intrinsically different spatial scales of the two sets of measurements. Gauge-radar comparisons are made between observations from a network of 11 rain gauges, which are clustered within a 3 km radius at the USDA North Appalachian Experimental Watershed near Coshocton, OH, and corresponding NEXRAD Stage III rainfall data collected by the NWS Ohio River Forecast Center. The methodology of error separation was employed both with and without considering small-scale spatial correlations, to examine the sensitivity of estimated impacts of area-point difference to different conceptualizations of the spatial rainfall structure. The dependence of the outcome of the approach on the climatology of precipitation systems is further assessed through comparative examination of the rainfall records during July and October of 2001. The implications for how to account for uncertainties when applying radar rainfall estimates to field scale and watershed scale analysis are discussed based on the findings.