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SUBPIXEL-SCALE RAINFALL VARIABILITY AND THE EFFECTS ON SEPARATION OF RADAR AND GAUGE RAINFALL ERRORS
Citation:
ZHANG, Y., T. ADAMS, AND J. V. BONTA. SUBPIXEL-SCALE RAINFALL VARIABILITY AND THE EFFECTS ON SEPARATION OF RADAR AND GAUGE RAINFALL ERRORS. Journal of Hydrometeorology. American Meteorological Society, Boston, MA, 8(6):1348–1363, (2007).
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Description:
One of the primary sources of the discrepancies between radar-based rainfall estimates and rain gauge measurements is the point-area difference, i.e., the intrinsic difference in the spatial dimensions of the rainfall fields that the respective data sets are meant to represent. The point-area difference is inherently linked to small-scale rainfall variations which, owing to instrumentation limitations, were often overlooked. This paper first presents an extension of the error separation method (EESM) that allows explicit paritioning of the errors in radar- and gauge-based representations of areal rainfall, and then on the basis of this framework investigates the link between sub-pixel scale rainfall variability and the perceived proportional contributions of radar- and gauge-related errors. The study utilizes records from 11 rain gauges within an approximately 1-km radius and corresponding NEXRAD Stage III data for four Hydrologic Rainfall Analysis Project (HRAP) pixels (with a size of 4km by 4 km). Application of EESM yields relative contribution of point-area difference in each pixel for July and October 2001, two months of contrasting precipitation characteristics. The results point to a strong seasonal dependence in the impacts of point-area difference. the study further suggests that accounting for the variations in the correlation structure within a pixel might be necessary for accurate delineation of the impacts of spatial rainfall variability and particularly so during the summer months.
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SUBPIXEL-SCALE RAINFALL VARIABILITY AND THE EFFECTS ON SEPARATION OF RADAR AND GAUGE RAINFALL ERRORS
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