Intercomparison of MJO Column Moist Static Energy and Water Vapor Budget among Six Modern Reanalysis Products
It has been recognized and documented that nonnegligible differences exist between reanalyses (RAs) in their representations of the MJO column-integrated moist static energy (MSE) or column water vapor (CWV) budget. In this study, we analyzed and compared the MJO MSE and CWV budget as well as the relevant mean state in six modern RAs: MERRA-1, MERRA-2, ERA-I, ERA5, CFSR, and JRA-55.
Notable inter-RA differences were found in the horizontal and vertical gradient of the mean MSE, which affects the MSE budget through the corresponding advection terms. The MSE budget terms directly affected by the model parameterization schemes exhibit high uncertainty.
This study conducts an intercomparison of the column-integrated moist static energy (MSE) and water vapor budget of the Madden–Julian oscillation (MJO) among six modern global reanalysis products (RAs). Results show a noticeable inter-RA spread in the mean-state MSE, especially its vertical structure. In all RAs, horizontal MSE advection dominates the propagation of the MJO MSE while column-integrated longwave radiative heating and vertical MSE advection are found to be the key processes for MJO maintenance. The differences in anomalous vertical velocity mainly contribute to the large differences in vertical MSE advection among the RAs. The budget residuals show large inter-RA differences and have non-negligible contributions to MJOmaintenance and propagation in most RAs. RAs that underestimate (overestimate) the strength of cloud–radiation feedback and the convective moisture adjustment time scale tend to have positive (negative) MJO CWV budget residual, indicating the critical role of these processes in the maintenance of MJO CWV anomalies.