CPOL radar-derived DSD statistics of stratiform and convective rain for two regimes in Darwin, Australia

A DSD-based indexing scheme has been developed to automate the classification of stratiform and convective rain types from CPOL radar data in Darwin, Australia, as well as to identify ‘mixed' rain type. We present here the basis for our newly developed DSD-based indexing technique, followed by the testing of the methodology by comparing our results with some previously published methods as applied to our datasets. Using our technique, statistics of the DSD parameters, namely histograms of log10(Nw) and Do, for convective and stratiform rain types across the build-up and monsoon periods were derived, and further separately for over-land and over-ocean regions.

The maximum value for mean Do (1.64 mm) and the broadest histogram width (0.32 mm) occurred for convective rain over land during the build up regime. The largest differences in Do and Nw were found to be for convective rain between build up and Monsoon regimes (independent of land or ocean areas). Stratiform rain histograms are very similar across regimes and land-ocean areas, with slight deviation for the build up regime over land. The main histogram characteristics of ‘mixed' rain type were closer to the convective rain type than to stratiform, across both regimes and land-ocean areas. Additionally, our Nw versus Do cluster of points (mean±σ) for convective rain agree very well with previously published range of values for maritime convective DSDs, thereby giving credence to our retrievals and our classification scheme.