Previous Research

MJO at different stages of the convective cycle

Date: 2023

In summary, four different types of convection are attributed to the energy recharge-discharge cycle of MJO. During the wet phases (P^'>0), the top-heavy ascending motion and negative shallow convection jointly stabilize the atmosphere by exporting the column MSE (⟨∂_t h⟩<0); whereas during the dry phases (P^'<0), the top-heavy descending motion and the positive shallow convection together destabilize the atmosphere through importing the column MSE (⟨∂_t h⟩>0). Moreover, the recharge (or discharge) phase leads the amplifying (or decaying) phase is essential to maintain a robust energy recharge-discharge cycle to drive the eastward propagating MJOs.

Distinct Features of MJO Event Types

Date: 2022

While the Weak Propagating (WP) MJO exhibits a somewhat similar circulation and MSE pattern, some discrepancies clearly exist. First, the amplitudes of circulation and MSE anomalies of WP MJO are significantly weaker than those of Strong Propagating (SP) MJO. Second, the downward and eastward extension of positive MSE anomalies in WP MJO appears to move further eastward (170°E) as compared to the SP MJO (150°E). Accordingly, the descending center is displaced further eastward across the dateline to force a wider Kelvin wave response in the lower troposphere as denoted by the further eastward extension of easterly winds and MSE anomalies on the longitude-latitude diagram (see Figs. a and b for comparison). In contrast, the Eastward Decaying (ED) MJO displays an extremely weak response and a more upright structure, with little sign of downward and eastward extension of positive MSE anomalies.