Increasing peak intensity of tropical cyclones passing through the Korean Peninsula

An increasing trend along with an abrupt increase in the peak intensity of tropical cyclones (TCs) passing through the Korean Peninsula (KP) are significantly detected from 1981 to 2020 and since 2003, respectively. Here we present observational evidence that such trend and shift are largely attributed with the increased passages of intense TCs in the KP during the mature boreal autumn (i.e., September-October, SO) and linked with the recent shift of the Pacific Decadal Oscillation (PDO) to its negative phase. A negative PDO during SO is related to environmental changes that are favorable for more intense TC passages in the KP including a weakened East Asian subtropical jet stream, weaker vertical wind shear, warmer subtropical sea surface temperature, and stronger low-level relative vorticity. Such findings are expected to provide new insights on understanding regional TC variability and ultimately, contribute to long range TC prediction initiatives in the KP region.