Considerable differences of the interannual variations for the tropical cyclone landfall over north and south East Asia in summer

Abstract

<p>Interannual variation of tropical cyclone (TC) landfall frequency is not consistent along the coast of East Asia, with large contrast of north and south East Asia coast regions in boreal summer. This study examines interannual variations of TC landfall frequency over north and south East Asia and identifies roles of the western North Pacific subtropical high (WNPSH) and TC genesis frequency associated with these variations. Although the total number of landing TC of north and south East Asia is similar, interannual variations of TC landfall frequency are relatively independent to each other, with the corresponding correlation coefficient north and south of 25°N is only –0.024 from 1979 to 2017. TC landfall over north East Asia is largely modulated by the circulation related to the WNPSH, while TC landfall in the south has no significant relationship with the WNPSH or other remote large-scale circulations. The WNPSH effectively regulates TC landfall in the north by modulating TC genesis east of the Philippines and steering flows. Nonetheless, the two factors have weak contradictory effects on TC landing in the south region. The frequency of TC genesis around the South China Sea directly connects to the TC landfall over south East Asia, which is modulated by the surrounding genesis environment, including relative humidity and relative vorticity. This work favors for a better understanding of the seasonal forecasts of TC landfall frequency and the subsequent climate service over East Asia.</p>