Exploring the Predictability of Boreal Winter Subseasonal Peak Precipitation over the South China Sea and Maritime Continent in the S2S Database

Tropical South China Sea (SCS)-Maritime Continent (MC) is one of the precipitation centers in the tropics during the boreal winter half year (NDJFMA). The abundant winter rainfall amount over this region involves multiple-scale phenomena such as the annual cycle, cold surges, ENSO, Madden-Julian Oscillation (MJO), and convectively coupled equatorial waves (CCEWs). This study focuses on analyzing the predictability of the subseasonal peak precipitation event in the SCS-MC region. The peak event is defined as a wet episode of time scale within the range of 10~60 days, during which the accumulated rainfall shows distinctly contribution to the seasonal totals. The occurrence time and mean precipitation intensity of the peak events are analyzed using CMORPH and ERA-interim datasets. The result suggests that the MJO and CCEWs have strong influence on the timing and intensity of the peak precipitation, while the terrain effect can overwhelm such large-scale modulation. The observational analysis result is applied to assess the predictability of peak events during two SCSTIMX (South China Sea Two Island Monsoon Experiment) winters in 2016/17 and 2017/18. The influence of tropical and extratropical waves and terrain effect are discussed.