资源环境科技发展态势分析平台

The evaporative moisture source for wintertime precipitation over southern China during 1979-2017 is determined using a Lagrangian methodology. The five most important moisture source regions, in descending order, are the South China Sea, southern China (local moisture recycling), southeastern Asia, the East China Sea, and the western North Pacific. The dominant mode of variability of moisture contribution appears at the interannual time scale, which is closely related to the El Nino Southern Oscillation variability. The conventional El Nino signal favors moisture transport from the surrounding moisture source regions through an enhancement of an anticyclonic anomaly over the western North Pacific, while El Nino Modoki drives moisture recycling over southern China by cutting off access to moisture sources from surrounding regions. A regime shift of the evaporative moisture source is identified to occur around 1991/1992, after which there was a significant eastward migration of the moisture source. This migration is closely related to the presence of a cyclonic anomaly over the South China Sea. Both the observational and experimental results reveal that the appearance of this cyclonic anomaly is due to the warming over the Maritime Continent during the last two decades.