New Publication: Tropical Cyclones Effects on Marginal Seas

Amid ongoing global warming, tropical cyclones (TCs) pose a heightened risk to marginal seas in mid and high latitudes. While considerable progress has been made in understanding TCs’ robust yet swiftly restoring impact on marginal seas, the question of whether TCs exert long-term influence and how they affect the seasonal evolution of these seas remain pivotal to explore. Using a well-calibrated FVCOM model, here we concentrate on a prominent feature of marginal seas (i.e., cold pools) and investigate the impact of Typhoon Lekima (2019) on their evolution in Bohai Sea, a typical marginal sea in the northwest Pacific Ocean. The reduced solar radiation and intensified vertical mixing induced by the typhoon significantly weakened the cold pools. More importantly, these cold pools failed to recover and continued to diminish as the solar and wind fields shifted seasonally, ultimately disappearing approximately 20 days earlier than the climatological average. Typhoon Lekima contributed primarily by strongly eroding the ocean stratification. This erosion, combined with the seasonally weakened solar radiation in early autumn, prevented the stratification from recovering. As a result, the mixing effects of subsequent strong winds were amplified, accelerating the premature dissipation of the cold pools. Consequently, TCs occurring during the transition between summer and autumn could significantly accelerate the seasonal evolution of marginal seas. This phenomenon is not unique to the Bohai Sea, similar patterns of early cold pool dissipation have been observed globally in marginal seas (e.g., the Bering Sea, North Sea, and Western Irish Sea). With the growing frequency and intensity of TCs affecting mid-high latitudes due to global warming, the catalytic influence of TCs on seasonal transition of marginal seas demands increasing attentions.