Self-enhancement of cold disasters in the Taiwan Strait: the role of transient air–sea interactions

Cold disasters in the Taiwan Strait (CDTS) occasionally impact ecology and aquaculture. Previous studies primarily attributed these events to variations in monsoon intensity and ENSO, but the physical mechanisms remain poorly understood. To address this gap, we investigate the 2008 CDTS using a coupled CROCO-WRF model, with a specific focus on how transient air–sea interaction (TASI) processes contribute to its onset and evolution. The model reasonably reproduced the 8.9 °C cooling documented by in situ measurements at the Penghu station. Without considering TASI, the simulation underestimated the cooling by 1.8 °C. Model’s results illustrate that the extreme cooling was primarily driven by the detachment of the China Coastal Current (CCC) toward the Chang-Yuen Rise. Coupled simulations further indicate that the cold patch reduced the air–sea temperature difference and weakened the monsoon winds. This weakened wind stress altered Ekman transport and further reinforced CCC detachment. A long-term analysis supports the presence of this self-enhancement effect. Compared with traditional approaches that treat the atmosphere as a fixed boundary, these findings underscore the pivotal role of TASI coupling in amplifying CDTS intensity, and provide valuable guidance for improving model-based forecasts and aquaculture management in the Taiwan Strait and similar monsoon-influenced coastal seas.