Spatial and temporal distribution of latent heating in the south-Asian monsoon region

Information from the TRMM-CSH and TRMM-2A12 datasets is used to examine the four-dimensional LH structures over the Asian monsoon region between 1998 and 2006. High sea surface temperatures, ocean-land contrasts and complex terrain produce large precipitation rates and atmospheric heating whose spatial and temporal characteristics are relatively undocumented. Analyses show interannual and intraseasonal variability of LH, with large amplitude intraseasonally-induced internal interannual variability in addition to a spatial dipole of LH anomalies between the equatorial Indian Ocean and Bay of Bengal regions occurring during the summer active and suppressed phases of the monsoon intraseasonal oscillation. Comparisons made between the TRMM-CSH and TRMM-2A12 datasets indicate differences in the shape of the vertical profile of LH. Comparison of TRMM-LH retrievals with observations made during the South China Sea Monsoon experiment shows high correspondence in the timing of positive LH values during rainy periods. Negative values of LH, associated with cooling, are not captured by any of the TRMM datasets. In summary, LH algorithms based on satellite information are capable of representing the spatial and temporal characteristics of the vertically integrated heating in the Asian monsoon region. However, the vertical distribution of atmospheric heating is not captured accurately throughout different convective phases. It is suggested that new algorithms are needed in order to describe periods of net cooling when there is no precipitation.