Projected Changes in the Pattern of Spatially Compounding Drought and Pluvial Events Over Eastern China Under a Warming Climate

The simultaneous occurrence of droughts and floods in neighboring regions amplifies the threats posed by droughts and floods individually. Nonetheless, few studies have been conducted to investigate the simultaneous occurrence of drought and flood events. Here we explore the spatiotemporal characteristics and the shift pattern of droughts and pluvials over Eastern China from a three-dimensional perspective, using the self-calibrated Palmer Drought Severity Index and the Climate Research Unit data set as well as four regional climate model simulations. We find that Eastern China experienced droughts and pluvials simultaneously in different locations during boreal summer, and it is projected to simultaneously experience more frequent and more intense droughts and pluvials under a warming climate. Specifically, we investigate the pattern of more pluvials in Southeast China and more droughts in Northeast China for the historical period of 1975-2004. This pattern dynamically evolves under climate warming: the pluvial-dominated regime shifts from Southeast to Northeast China, while the drought-dominated regime shifts from Northeast to Southeast China. The weakening strength of the western Pacific subtropical high and a northward displacement of the monsoon rain belt may both contribute to the pattern of more pluvials in Northeast China and more droughts in Southeast China. These findings provide insights into the development of adaptation strategies and emergency response plans for enhancing society's resilience to the spatial co-occurrence of dry and wet extremes.

Automated summary

Simultaneous occurrence of drought and flood events in Eastern China amplifies threats and is projected to become more frequent and intense under climate warming. Historical pattern shows more floods in Southeast China and more droughts in Northeast China, but climate warming will shift this pattern. Weakening of western Pacific subtropical high and northward displacement of monsoon rain belt may contribute to the changes in drought and flood patterns.