A better understanding of the relationship between precipitation rate at the levels scanned by the WSR-88D and precipitation rate at or near the surface is needed to improve these estimates, an effort that requires knowledge of the vertical profile of precipitation rate throughout the precipitating cloud. To address this issue, our study uses WSR-88D data from San Francisco (KMUX) in combination with observations collected during the 1998 California Land-falling Jets (CALJET) experiment. The key CALJET observations are from a 10 cm vertically pointing Doppler radar located in the coastal mountains north of San Francisco. This instrument provides the vertical structure of precipitation from the surface up to cloud top, including those regions below the scanning level of KMUX.
Analysis of the vertically pointing Doppler radar data has revealed distinctly different vertical precipitation structures in the cool, warm, and cold sectors of land-falling extratropical cyclone systems. In addition to variations in the height of the bright band, the rate of reflectivity decrease with height above the bright band differs between each of these regimes. These results have relevance to the QPE problem since this type of information can be used to make corrections to flawed WSR-88D precipitation estimates. In this presentation, we will show how the corrections are calculated and applied, the subsequent improvements in QPE, and possible limitations in the technique.
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