A New Method for Deducing Hydrometeor-Size Distributions and Vertical Air Motions from Doppler Radar Measurements at Vertical Incidence

Abstract

Using the hypothesis of an exponential hydrometeor-size distribution characterized by the two classical intercept (N0) and slope (?) parameters, a method is presented for simultaneously deducing N0, ? and the vertical air velocity w from a Doppler spectrum measured at vertical incidence. It is based on a least-squares fitting of a theoretical spectrum depending on N0, ? and w, which are the adjusted parameters, to the measured one. The principle, sensitivity and limitations of the method are discussed in detail. It is expected that this method applies mainly to the case of stratiform rain.