Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

AbstractThe budget of column-integrated moist static energy (MSE) is examined in wavenumber-frequency transforms of longitude-time sections over the tropical belt. Cross spectra with satellite-derived precipitation (TRMM-3B42) are used to emphasize precipitation-coherent signals in reanalysis (ECMWF-Interim, ERAI) estimates of each term in the budget equation.Results reveal different budget balances in convectively coupled equatorial waves (CCEWs) as well as in the Madden–Julian oscillation (MJO) and tropical depression (TD)-type disturbances. The real component (expressing amplification or damping of amplitude) for horizontal advection is modest for most wave types, but substantially damps the MJO. Its imaginary component is hugely positive (it acts to advance phase) in TD-type disturbances, and is positive for MJO and Equatorial Rossby (ERn1) wave disturbances (almost negligible for the other CCEWs). The real component of vertical advection is negatively correlated (damping effect) with precipitation wi...