Eddy generation mechanism in the eastern South China Sea

Abstract

Mesoscale eddy generation mechanisms in the eastern South China Sea (ESCS) are investigated using altimetry observations and solutions of a nonlinear, 1½-layer reduced-gravity model. We estimate the relative roles of the wind forcing in the interior South China Sea (SCS) and the remote forcing from the western tropical Pacific (WTP) in eddy generation in the ESCS. Model solutions show that the high-frequency wind in the interior SCS is the primary forcing for eddies, which explains about 54% of the mesoscale eddies generated in the ESCS. Signals from the WTP also play an important role. Wind-driven equatorial signals reach the west coast of Luzon Island through the Sibutu Passage and Mindoro Strait. The reflected Rossby waves from the west coast of Luzon Island propagate westward, become unstable, and turn into eddies. The signals driven by high-frequency wind from the WTP explain about 40% of the mesoscale eddies generated in the ESCS. The high-frequency wind forcing in both the SCS and the WTP is important for eddy generation in the ESCS.