Modulation of landfalling tropical cyclone activity in the western North Pacific by North Atlantic tripolar SST

Abstract

Previous research on the effects of Atlantic sea surface temperature (SST) on tropical cyclones (TCs) in the western North Pacific (WNP) has primarily focused on the tropical Atlantic region. This study investigates the relationship between the extra-equatorial North Atlantic tripole (NAT) sea surface temperature anomaly (SSTA) pattern and landfalling TCs in the WNP. The findings reveal a significant positive lead-lag correlation between the negative–positive–negative NAT SSTA pattern and the genesis of landfalling TCs in the WNP. In high NAT years, more TCs form in the WNP and recurve northeastward to make landfall over the Korean Peninsula and Japan, while fewer TCs move westward or northwestward. The NAT tropical cold SSTA transmits signals to the WNP and modulates TC genesis via two ways: the eastward pathway through the North Indian Ocean and the westward pathway through the eastern North Pacific. This enhances cyclonic vorticity in the WNP monsoon trough region, facilitating increased TC genesis frequency in the region and thereby increasing the genesis frequency of landfalling TCs. Furthermore, the NAT SSTA influences the tracks of these landfalling TCs. The NAT SSTA pattern persists into summer, triggering a mid-high latitude teleconnection wave train that propagates downstream. This induces an anomalous anticyclone over Northeast Asia and an accompanying cyclonic circulation to its west. This circulation leads to the recurving of TC tracks rather than a northwestward or westward direction. The results suggest that the NAT SSTA is a potential predictor of TC formations and track patterns in the WNP.