Seasonal Contrasts in the Trends of Landfalling Tropical Cyclone Track Density in China (1949–2023)

The landfalling tropical cyclone track density (LTD) in China has shown an overall decreasing trend over the western North Pacific (WNP) while revealing an increase along the coastal East China (CEC) in the past several decades. This study further elucidates that the long-term LTD trend in the CEC exhibits a pronounced seasonal contrast that there is a significant increase from August to October, whereas a decline is observed from May to July. This seasonal reversal in the CEC LTD trend is attributed to the northward migration of an intensified diabatic heating source from May to October under global warming. This result is supported by a linear baroclinic model that incorporates realistic precipitation trends to parameterize diabatic heating over the WNP. Our finding underscores the critical role of local warming in modulating LTD trends, emphasizing its seasonal dependence rather than relying solely on sea surface temperature changes.