The present study explores the modulation of convective and stratiform precipitation by convectively coupled equatorial waves. We take two approaches to this problem. First, cross-spectral analysis is conducted. The phase relationships and covariance of water vapor and dynamical fields with the microwave-retrieved rainfall are focused on. Second, TRMM-PR data are used to obtain direct evidence. The phase and amplitude of each wave type disturbances (Kelvin, Rossby, MJO, etc.) are determined from space/time filtered TRMM-3B42 rainfall data, following the method by Wheeler and Kiladis (1999).

Results suggest that higher-frequency waves such as the Kelvin wave (especially the slower part of the spectral peak) and the inertio-gravity wave families modulate stratiform precipitation especially much, presumably by modulating organized precipitation systems in which stratiform rain is most prevalent. Consistently, these waves also modulate mid-tropospheric divergence a lot.

In contrast, slower and more rotational (Rossby, MJO, and mixed) waves mainly modulate convective rain, and also mainly modulate wind divergence near the surface and tropopause. These slower waves also have a stronger signature in column precipitable water, perhaps indicating a more advective mechanism for motion of these disturbances.