Analysis of Rain Classifications over the Tropics by Version 7 of the TRMM PR 2A23 Algorithm

抄録

 The Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) 2A23 algorithm attempts to classify rain echo as stratiform or convective. Updates to the 2A23 algorithm for Version 7 (V7) have resulted in an increase (decrease) in the fraction of rain echo classified as convective (stratiform) compared with the previous version of the algorithm. This is caused in part by more shallow non-isolated echoes, which exhibit strong concentrations over the Pacific intertropical convergence zone (ITCZ), being classified as convective in V7. The tropics-wide (20°N-20°S) stratiform rain fraction has decreased correspondingly from 40% to 38% between Version 5 (V5) and V7. It is suggested that two additional stratiform categories could be considered convective because of the prevalence of warm-rain processes in each, particularly, higher altitude rain over mountainous terrain and shallow non-isolated rain over tropical oceans; this would decrease the tropics-wide stratiform rain fraction to 35%.