Vertical Structure and Transient Behavior of Convective–Stratiform Heating in TOGA COARE from Combined Satellite–Sounding Analysis

Abstract

Datasets of daily high-resolution upper-air soundings and Special Sensor Microwave/Imager (SSM/I) passive microwave measurements from the Tropical Ocean and Global Atmosphere Coupled Ocean?Atmosphere Response Experiment (TOGA COARE) intensive operation period are used for large-scale diagnostic budget calculations of the apparent heat source (Q1), the apparent moisture sink (Q2), and latent heating to investigate the mechanisms of diabatic heating and moistening processes within the TOGA COARE Intensive Flux Array (IFA). Latent-heating retrievals are obtained from The Florida State University SSM/I-based precipitation profile retrieval algorithm. The estimates are correlated well with heating calculations from the soundings in which approximately 70% of the total heating arises from latent heat release. Moisture-budget processes also have a strong relationship with the large-scale environment, in which drying from condensation is mainly balanced by large-scale horizontal convergence of moisture flux. It is found that there may be more convective activity in summer than in winter over the tropical region of the western Pacific Ocean. Results also show that Q1 and Q2 exhibit a 20?30-day oscillation, in which active periods are associated with strong convection. Comparisons of the Q1?Q2 calculations over IFA are made with a number of previously published results to help to establish the similarities and differences of Q1?Q2 between the warm pool and other regions of the Tropics. The Q1?Q2 budget analyses over IFA then are used to study quantitatively the detailed vertical heating structures. Cumulus-scale heating?moistening processes are obtained by using published radiative divergence (QR) data, retrieved latent heating, and the Q1?Q2 calculations. These results show that cumulus-scale turbulent transport is an important mechanism in both heat and moisture budgets. Although daily estimates of eddy vertical moisture flux divergence are noisy, by averaging over 7-day periods and vertically integrating to obtain surface latent heat flux, good agreement with measured surface evaporation is found. This agreement demonstrates the feasibility of estimating averaged eddy heat?moisture flux profiles by combining satellite-derived rain profile retrievals with large-scale sounding and QR data, a methodology that helps to shed light on the role of cumulus convection in atmospheric heating and moistening.