Our recent understanding about the eddies in the South China Sea

Abstract

Features of eddy kinetic energy (EKE) in the South China Sea (SCS) are discussed using geostrophic currents estimated from maps of sea level anomalies of the TOPEX/Poseidon altimetry data. A high EKE is identified in the southeast off Vietnam coast with the highest values about 1400 cm/sup 2//sec/sup 2/ in both summer and autumn. This high EKE is caused by the instability of the current axis moving back and forth along the Vietnamese coast in these seasons. There exists another high EKE region in winter time in the northeastern SCS, in vicinity of the Luzon Strait. It is generated by the eddy activities initiated by the time-dependent Kuroshio intrusion over there and accumulates more than one third of the annual EKE amplitude. The transition of the upper circulations is evidenced quantitatively by the directions of the major axis of velocity variance ellipses and the most transiently adjusted circulations happen in the two aforementioned regions. This confirms that the monsoon-driven circulation adjustment favors the eddy activities in the SCS.