Diabatic Heating Distributions in the Tropics for Studies of Intraseasonal Phenomena

Satellite estimates of atmospheric latent+eddy heating (Q1-QR) and radiative heating (QR) are combined to yield estimates of the apparent heat source (Q1). The latent+eddy and radiative heating estimates rely on cloud and precipitation information from TRMM Microwave Imager (TMI) data, with additional cloud information supplied by the TRMM Visible and Infrared Scanner (VIRS) and clear-air environmental properties from NCEP reanalyses. Comparisons of the diabatic heating estimates to those derived primarily from the TRMM Precipitation Radar (PR) and from rawinsonde diagnostic budgets are favorable, although some biases due to differences in sampling and the limited sensitivity of the TMI are noted.

Recently, a ten-year database of precipitation and diabatic heating has been constructed using TRMM observations from 1998-2007, as part of NASA's Energy and Water cycle Study (NEWS) program. Initial applications of this dataset have been the delineation of the seasonal cycle in the tropics/subtropics, the distribution of heating anomalies associated with the phases of ENSO, and the progression of heating in the Madden Julian Oscillation. The focus of our presentation will be comparisons of precipitation, Q1, Q1-QR, and QR from the diabatic heating dataset and the Modern Era Retrospective-Analysis for Research and Applications (MERRA) for studies of the MJO.