Public Research Seminar by Earth, Ocean and Atmospheric Sciences (EOAS) Thrust, HKUST (GZ) - Multi-Scale Tropical Climate System: From ENSO and MJO to Tropical Cyclones

The El Niño-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO) are two major tropical climate variability with a period of 2-7 years and 20-100 days, respectively. They profoundly influence global weather and climate—affecting phenomena from hurricane formation to extreme rainfall and drought, and are major sources of subseasonal to seasonal climate predictability. During El Niño events, strong bursts of westerly wind anomalies often appear in the western-central equatorial Pacific, and these “westerly wind bursts (WWBs)” can kick-start and intensify the event. The precise causes of these bursts, however, have remained unclear. 
In this talk, he will show how the MJO and tropical cyclones act in tandem to generate these bursts, and more importantly, how this process is modulated by evolving background sea surface temperatures. He will then demonstrate how these new insights shed light on the formation mechanisms of extreme El Niño events, including a “turbo charger” that rapidly recharges equatorial ocean heat content preceding these extremes. In addition, He will present a new method for quantifying the effect of stochastic processes like the MJO on ENSO evolution, using a set of climate model ensemble hindcasts. Finally, he will talk about why changes of the MJO may make tropical cyclones more predictable on the subseasonal timescale under future global warming.