Sensitivity of an automatic procedure for hydrometeor classification

The purpose of this paper is to present details of the meteorological radar algorithm for classification of hydrometeors and a methodology for sensitivity analysis to the various polarimetric variables used for classification. The classification algorithm described belongs to the “fuzzy logic” family. In its essence a classifier assigns (maps) an observed point X in the multiparameter space to a class j (which refers to the bulk hydrometeor type such as rain, hail, graupel, snow, etc.). In this paper the point X has for coordinates the following six variables: (1) the reflectivity factor for horizontally polarized waves Z_h, (2) the differential reflectivity Z_DR, (3) the specific differential phase K_DP, (4) the cross correlation coefficient between the horizontally and vertically polarized (copolar) waves ρ_hv(0), (5) the linear depolarization ratio L_DR, and (6) the environmental temperature T. The crux of a hydrometeor classification scheme is to partition this six-dimensional space of observed variables into subsets such that each can be associated with a specific hydrometeor type (j). An obvious solution is to decouple the variables and consider each individually and then make a final judgement on the basis of weighted averages