Eddies in the Northwest Subtropical Pacific and Their Possible Effects on the South China Sea

摘要

Based on an analysis of drifter data from the World Ocean Circulation Experiment during 1979-1998, the sizes of the eddies in the North subtropical Pacific are determined from the radii of curvature of the drifter paths calculated by using a non-linear curve fitting method. To support the drifter data results, Sea Surface Height from the TOPEX/POSEIDON and ERS2 satellite data are analyzed in connection with the drifter paths. It is found that the eddies in the North Pacific (18°-23°N and 125°-150°E) move westward at an average speed of approximately 0.098 ms~(-1) and their average radius is 176 km, with radii ranging from 98 km to 298 km. During the nineteen-year period, only 4 out of approximately 200 drifters (2%) actually entered the South China Sea from the area adjacent to the Luzon Strait (18°-22°N and 121°-125°E) in the winter. It is also found that eddies from the interior of the North Pacific are unlikely to enter the South China Sea through the Luzon Strait.