Madden–Julian Oscillation: Its Discovery, Dynamics, and Impact on East Asia

In this review article, we pay primary attention to innovative works in the Madden–Julian Oscillation (MJO) field done by Chinese scientists. The historical aspect of discovery of the MJO and earlier studies of its dynamics by Chinese scientists are first described. It is followed by the description of recent advances in MJO propagation and initiation dynamics. For MJO eastward propagation, two types of the moisture mode theory are introduced. The first one emphasizes the effect of zonal asymmetry of perturbation moisture in the atmospheric boundary layer and the second one emphasizes the zonal asymmetry of column integrated moisture static energy (MSE) tendency. The mechanisms for MJO initiation over the western Indian Ocean include three distinctive processes: lower tropospheric moistening due to horizontal advection caused by preceding suppressed-phase MJO, midlatitude Rossby wave activity flux convergence in the upper troposphere originated from the Southern Hemisphere, and a delayed sea surface temperature feedback in association with a preceding opposite-phase MJO. The impacts of MJO on low-frequency variability of precipitation and temperature and associated extreme events in East Asia are also discussed.