Response of Cyclonic Eddies to Typhoon Surigae and Their Weakening Effect on the Kuroshio Current in the Western North Pacific Ocean

Abstract

This study investigated the dynamic and thermal responses of cyclonic eddies (CEs) to Typhoon Surigae in the western North Pacific Ocean using satellite data and a coupled ocean–atmosphere model. Observations and simulations revealed that the typhoon enhanced the two preexisting CEs (C1 and C2). After the typhoon passed the two eddies, the sea surface height (SSH) lowered and the eddy velocity increased above 200 m. C1 was stretched with elliptical deformation accompanied by an SSH trough and jets on the sides of the typhoon track at the eddy edge. The comparative experiments indicated that the typhoon caused the SSH of C1 and C2 to lower by 53.52% and 25.14% compared to conditions without the typhoon, respectively, and the kinetic energy of C1 and C2 to increase by 12 times and 65.76%, respectively. The positive vorticity anomaly input from the typhoon to the CEs was the main mechanism for the enhancement of the CEs. The enhanced CEs modulated the typhoon-induced sea surface temperature (SST) cooling, causing the temperature within the eddies to decrease by upwelling and mixing, and the SST cooling became significant at the center of the CEs and propagated westward with the eddies. This study also revealed that typhoons can significantly perturb eddy dynamic structures by enhancing or generating cyclonic cold eddies and eradicating anticyclonic eddies, thereby weakening the Kuroshio Current transport via eddy–Kuroshio interactions.