Intercomparison of the Column Moist Static Energy Budget of the MJO among Six Modern Reanalysis Products

Abstract:

This study conducts an intercomparison of six modern reanalysis products (RAs) with a focus on the column-integrated Moist Static Energy (MSE) budget of the Madden-Julian Oscillation (MJO). The inter-RA differences in the mean MSE, MJO MSE anomalies, individual MSE budget terms and their relative contributions to the propagation and maintenance of MJO MSE anomalies are examined. Also examined is the relationship between MJO column water vapor (CWV) budget residual and two parameters that characterize cloud-radiation feedback and moisture-convection coupling.

Results show noticeable inter-RA spread in the mean state MSE, especially its vertical structure. In all RAs, horizontal advection dominates the propagation of the MJO while column-integrated longwave heating is found to be the key to MJO maintenance. The processes associated with deep convection show high uncertainty. The differences in the mean vertical MSE gradient greatly affect vertical MSE advection term. The role of surface latent heat flux on MJO maintenance varies significantly among RAs. MJO MSE budget residuals have non-negligible contributions to MJO maintenance and propagation in most RAs. We find that MJO CWV budget residual shows a negative linear relationship with the cloud radiation feedback strength and the convective adjustment time scale. Our results emphasize that a correct representation of interactions among moisture, convection, cloud, and radiation is the key for an accurate depiction of the MJO in RAs.