Eddy-Kuroshio interaction processes revealed by mooring observations off Taiwan and Luzon

Abstract

The influence and fate of westward propagating eddies that impinge on the Kuroshio were observed with pressure sensor-equipped inverted echo sounders (PIESs) deployed east of Taiwan and northeast of Luzon. Zero lag correlations between PIES-measured acoustic travel times and satellite-measured sea surface height anomalies (SSHa), which are normally negative, have lower magnitude toward the west, suggesting the eddy-influence is weakened across the Kuroshio. The observational data reveal that impinging eddies lead to seesaw-like SSHa and pycnocline depth changes across the Kuroshio east of Taiwan, whereas analogous responses are not found in the Kuroshio northeast of Luzon. Anticyclones intensify sea surface and pycnocline slopes across the Kuroshio, while cyclones weaken these slopes, particularly east of Taiwan. During the 6 month period of overlap between the two PIES arrays, only one anticyclone affected the pycnocline depth first at the array northeast of Luzon and 21 days later in the downstream Kuroshio east of Taiwan. Key Points Eddy-Kuroshio interaction is observed with 11 pressure sensor-equipped inverted echo sounders Eddy-influence weakens across the Kuroshio east of Taiwan and northeast of Luzon Eddy-influence causes seesaw-like SSHa changes across the Kuroshio most obviously east of Taiwan