Bi-modal structure and evolution of tropical diabatic heating profiles

Tropical diabatic heating profiles estimated using sounding data from eight field campaign, four global reanalyses, and four TRMM retrievals were diagnosed and compared to document their common and prevailing structure and variability that are relevant to the large-scale circulation. The first two modes of a rotated empirical orthogonal function (REOF) analysis, one deep, one shallow, represent well the total variance. These two modes were used to describe the heating evolution, which led to three composited heating profiles that are considered as prevailing large-scale heating structures. They are, respectively, shallow and bottom heavy, deep and middle heavy, and stratiform-like (with low-level cooling) and top heavy. The amplitudes and occurrence frequencies of the shallow, bottom-heavy heating profiles are comparable to those of the stratiform-like, top-heavy ones. The two leading REOF modes exhibit ubiquity in space and across most of the data sets. Implications of the ubiquity are discussed.