Structural Evolution in Heating Profiles of the MJO in Global Reanalyses and TRMM Retrievals

Abstract

Diabatic and latent heating profiles from four global reanalyses and three Tropical Rainfall Measuring Mission (TRMM) algorithms were compared: first generally for the tropics and then in the context of the Madden?Julian oscillation (MJO). Most of them exhibit three heating maxima corresponding to known convection centers over South America, Africa, and the Indian?western Pacific warm pool, but they still differ substantially in many ways. Most noticeably, a double-peak vertical structure with one peak in the upper and the other in the lower troposphere and relative weak heating over the Maritime Continent in comparison to heating over the Indian and western Pacific Oceans are clearly seen in some heating data but absent in others. Heating profiles associated with the MJO were diagnosed through composites and case studies. The composites were constructed as functions of MJO phases at three longitudes representing the Indian Ocean, Maritime Continent, and western Pacific, respectively. Four MJO events were chosen for the case studies, two over the Indian Ocean and two over the western Pacific. No consistent structural evolution of heating profiles through the life cycle of the MJO could be found either among different datasets in their composites at a given longitude and their case studies for a given individual MJO event or among different longitudes and MJO events within a given dataset. Nonetheless, the previously reported westward tilt in the heating field of the MJO, composed of low-level heating preceding deep heating in an active phase of the MJO and upper-level heating immediately following the active phase, is more likely to be observed over the western Pacific than other locations. The discrepancies among the datasets illustrate the infancy of estimating diabatic heating profiles from satellite observations and the need to improve the quality of the data assimilation products.