Amplifying subtropical hydrological transition over China in early summer tied to weakened mid-latitude synoptic disturbances

Abstract The rainy season over southern China (SC) begins with the onset of South Sea monsoon around mid-May. We demonstrate here that SC precipitation exhibits a notable drying (wetting) trend prior to (after) onset, leading more abrupt thus amplified hydrological transition in early summer. contrasting trends are largely driven by recent decline mid-latitude synoptic eddy activity. Weakened disturbances suppress frontal activities before facilitating trend, and enhance spatial stationarity monsoonal front after wetting trend. CMIP6 models general fail capture between two periods. In where both activity well captured, amplification is projected continue into late 21 st century. Our results highlight footprints hemispheric-scale climate change regional hydroclimate obvious challenges faced capturing such footprints.