On the Separation of Tropical Convective and Stratiform Rains

This work resolves an apparent conflict between the results of Yuter and Houze and Atlas et al. concerning relations between radar reflectivity factor Z and rainfall rate R derived from essentially the same drop size data observed aloft during the Tropical Ocean and Global Atmosphere program's (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE). It is shown that the single relation found by Yuter and Houze is founded upon distinct underlying Z–R relations for stratiform and convective rains. This result occurs despite the fact that errors in rain types classified by different methods and the variability of the effective drop sizes within each type tend to obscure the distinction. This newly found agreement between the two distinctly different methods of analysis also suggests the essential equivalence of the classification methods of Steiner et al. (based upon the existence of a maximum in the observed reflectivity field) and of Atlas et al. (based upon the magnitude of the drafts). However, further trials are necessary to demonstrate the generality of this equivalence.