Effect of vertical moist static energy advection on MJO eastward propagation: sensitivity to analysis domain

Abstract

Previous studies have shown great uncertainty in assessing the effect of vertical moist static energy (MSE) advection term to the zonal asymmetry of MSE tendency. This study addresses this issue by qualitatively assess the fractional contribution of the vertical MSE advection to the zonal asymmetric pattern of the MSE tendency field, and how its contribution depends on the choice of the analysis domain, based on both observational and numerical simulation results. It is shown that the vertical MSE advection indeed plays a critical role in generating the zonal asymmetry of MSE tendency, accounting for 60% of the total MSE tendency field in observation and even more in aqua-planet simulations. It is indicated that the underestimated contribution from vertical MSE advection by some previous studies is attributed to the unphysical selection of analysis domain for the zonal asymmetric MSE tendency pattern.