Western Pacific Subtropical High Modulates Regional Hydroclimate Changes on Multiple Timescales Over Central China

Abstract

Understanding regional hydroclimate and its driving mechanisms is important for accurate projections of hydrology variations in the future. This study provides a regional hydroclimate record over the past 5.7 ka based on speleothem climatic proxies from Jiuxian cave, central China. Our study suggests that coupling between sea surface temperatures (SST) of the Indo-Pacific warm pool (IPWP) and the positioning of the Western Pacific Subtropical High (WPSH) modulate both spatial heterogeneity of hydrological conditions on millennial-centennial time scales and the strength of hydroclimatic events in central China. Higher SSTs in IPWP drive northeastward movements of WPSH, causing increased rainfall in the mid-lower reaches of the Yellow River Valley, but decreased rainfall in the mid-lower reaches of the Yangtze River Valley, and vice versa for lower SSTs. In addition, enlarged variability of WPSH associated with that of SSTs in IPWP can enhance the strength of the abrupt hydroclimate events. Our findings highlight the important role of WPSH in the strengths and spatial heterogeneity of regional hydroclimate.