ABSTRACT

The column-integrated moist static energy (MSE) budget associated with the northward-propagating boreal summer intraseasonal oscillation (BSISO) is diagnosed for the Bay of Bengal (BoB) and western North Pacific (WNP) regions. Results show that an active BSISO convection is generally in phase with a positive column-integrated MSE perturbation, while the tendency of the latter corresponds to a warm SST anomaly and both locate to the north of the active convection by a 90° phase. The zonal (meridional) advection process dominates the increasing of the column-integrated MSE over the BoB (WNP) area. The surface latent heat flux also contributes positively over the WNP area but negatively over the BoB area. In the existence of the northwest/southeast-tilted structure of the BSISO rainband, the distinct background wind flows and specific land-sea distributions are mainly responsible for such differences.