ABSTRACT
Precipitation, an important input for land surface processes such as the hydrologic cycle and vegetation growth, is characterized by high spatial and temporal variability. Traditionally, precipitation measurements are available at rain gauge points, which are usually too sparsely distributed to capture spatial variability; therefore, these point data need to be interpolated to estimate the spatial distribution of precipitation. The production of Next Generation Radar (NEXRAD) precipitation products involves several major procedures and various “stages” of processing by the NWS. First, a radar system measures the reflectivity of a volume of air by scanning over a fixed polar grid with a radial resolution of 1° in azimuth by 1 km in range. NEXRAD performance is influenced by many factors such as range degradation, beam blockage in complex terrain, and quality of rain gauge data incorporated in NEXRAD. The errors associated with rain gauge observations may also lead to uncertainty of evaluation of NEXRAD performance.
