East Asian monsoon and Pacific basin dynamics jointly regulate boreal winter marine cold spells in the Taiwan Strait.

Marine cold spells (MCSs), characterized by pronounced seawater temperature declines, are representative marine responses to atmospheric and climatic extremes. Notably, during the boreal winter, MCSs in the Taiwan Strait (TS) have caused substantial economic losses due to the concurrence of juvenile development stages in mariculture and labor shortages during China's New Year vacation. Understanding the spatio-temporal features of MCSs and the underlying mechanisms is imperative for mitigating the associated economic detriments. This study, for the first time, delineates two MCS hotspots in the northeastern and western TS, based on various sea surface temperature datasets. Our findings reveal a notable frequency and intensity of MCSs in the 1980s, followed by a period of suppressed phase, reaching a historic low point in 2002. However, contrary to expectations of the overall trend of global warming, MCSs have experienced a resurgence since 2002, with a pronounced focus on the western coast of the TS. Diagnostic analyses suggest that the Winter East Asian Monsoon-driven cold current and the Pacific basin scale dynamic-forced warm current jointly regulated the spatio-temporal features of the MCSs. This study contributes a novel perspective on the impacts of climate change on extreme marine events along subtropical coastal areas.