A Method for Improving Rain Estimates from Vertical-Incidence Doppler Radar Observations

Abstract

For an exponential drop size distribution, the mean Doppler velocity at vertical incidence, after correction for vertical air motion, depends only on the slope of the distribution. The intercept of the distribution can then be deduced from the radar reflectivity and the slope and the intercept can be used to compute the rainwater content and the rainfall rate. The necessity of correcting for the vertical air motion limits the method to stratiform rain where it may be obtained by VAD methods or may be small enough to be neglected. Two examples of the use of the method are presented.