On the Mechanism of South China Sea Warm Current and Kuroshio Branch in Winter---Preliminary Results of 3-Dbaroclinic Experiments

Longfei Ye
1994 Terrestrial, Atmospheric and Oceanic Sciences  
The circulation in the South China Sea was thought to be mainly wind driven current controlled by monsoons. But recent observations reveal two currents in opposite directions, namely the northeastward South China Sea Warm Current (SCSWC) and the southwestward Kuroshio South China Sea Branch (KSCSB), flowing along the steep continental slope in the northern South China Sea. Surprisingly, the SCSWC flows against the strong northeast monsoon and becomes even stronger in winter. This may be
more » ... This may be explained by a nthermodynamic model" based on the in trusion of the Kuroshio through the Bashi Strait. Warm waters extend into the South China Sea in a tongue shape formation along the isobaths of the continental slope and, therefore first, head northwestwards and then bend southwestwards. Hence, the KSCSB is fQrmed by "topography trapping" due to the conservation of potential vorticity. The baroclinic effect due to the strong temperature gradient thus developed by these warm waters against the cold waters near the coast of South China drives the SCSWC strong enough against the monsoon in winter. Results of 3-D baroclinic (in contrast to barotropic) prognostic numeri cal experiments are adequate to prove not only these ideas qualitatively but also the existence of cold eddies behind the intruding warm water tongue. Nevertheless further quantitative investigations are required to compare with observations although the circulation in this area is very sensitive to many factors subjected to seasonal and interannual variations. (
doi:10.3319/tao.1994.5.4.597(o) fatcat:5e4k36wf45ao7ci25jzftw2qeu