Solar modulation of hydroclimatic patterns in eastern China under influences of the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation

Abstract

This study explores how solar activity modulates hydroclimatic patterns in eastern China (ECHPs) across different phases of the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO), using the Community Earth System Model-Last Millennium Ensemble dataset and historical hydroclimate reconstructions. Under strong solar activity, positive phases of the AMO or PDO are associated with meridional dipole ECHPs, causing wet conditions in the southern Yangtze River and dry conditions in the north. This is driven by Eurasian-like teleconnection patterns and western Pacific anticyclonic anomalies, enhancing moisture transport to the southern Yangtze River. Negative AMO or PDO phases produce similar dipole ECHPs, with less pronounced effects in the southern Yangtze River, linked to positive phases of East Asia/Pacific-like teleconnection patterns and subtropical Pacific cyclonic anomalies. Under weak solar activity, positive PDO or negative AMO phases lead to reversed dipole ECHPs compared to those observed under strong solar forcing, with wet conditions in the northern Yangtze River and dry conditions in the south. Negative PDO or positive AMO phases result in meridional tripole ECHPs, with alternating dry-wet-dry conditions. All scenarios reveal changes in vertical moisture dynamics, with wind divergence and convergence patterns closely aligning with the observed ECHPs. The findings can improve predictive models for future hydroclimates and enhance adaptation strategies in East Asia.