One important question for the study of the Madden-Julian Oscillation (MJO) is: What is the driving mechanism of the MJO? In the previous wave-convection instability theories, the five components of the diabatic heating, namely, the free troposphere moisture convergence, the boundary layer moisture convergence, the surface heat flux, the local change of moisture, and the radiative heating, have been emphasized by wave-CISK, frictional wave-CISK, WISHE, charge-discharge, and cloud-radiation interaction mechanisms, respectively. In this study, the sounding array heat and moisture budgets from the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE), supplemented by multi-year observation of tropical precipitation, temperature, circulation and surface fluxes, are used to study the role of each of the five heating components in amplifying the coupled Kelvin-Rossby wave in the heating centers of the MJO.

Among the five heating components, the free troposphere moisture convergence, the boundary layer moisture convergence and the surface latent heat flux are positively correlated with the upper troposphere temperature, suggesting that they amplify the MJO wave. The local change of moisture and the upper troposphere radiative heating lag the upper troposphere temperature by nearly a quarter cycle, suggesting that they neither amplify nor damp the MJO wave.