Statistical Models of Summer Rainshowers Derived from Fine-Scale Radar Observations

Abstract

This study concerns the statistical modeling of rain cell characteristics based on high-resolution radar measurements of the cell structure. The fine-scale three-dimensional structure of summer rainshowers in the mid-Atlantic region has been analyzed leading to statistical descriptions of the rain cells in terms of a variety of physical cell parameters. Core reflectivity profiles, contour area and altitude extent of the cells have been generated along with the frequency of occurrence for various storm classes and categories. Rain cell classes and categories were based on the reflectivity levels at essentially ground level. Cell populations which include all the cells observed were also treated. The mean and median core reflectivity profiles are essentially constant up to altitudes of 4?6 km and then fall off with increasing altitude and follow an orderly progression with cell category. The area of the reflectivity contours about the core value was found to follow an exponential relationship. The statistical descriptions of the rain cells for the mid-Atlantic region were compared to those from previous investigators at other geographical locations. In terms of core reflectivity profiles, the data for the various locations are rather similar. Significant differences, however, are evident in the altitude extent. Finally, simplified models of rain cells based on the statistical descriptions are developed for the different rain categories as a function of frequency of occurrence.