Seasonal Variation Of The Water Exchange In Luzon Strait

My dissertation consists of five parts. Review on the topic is given in the first part. In the second part I review the study object and the method of the field observation on this topic. In the third part the in situ observation data, the altimetry data and the satellite- tracked drifting buoys data are analyzed. Princeton Ocean Model is used here to simulate the seasonal variation of the velocity field in the Luzon Strait and relative numerical experiments are conducted in the fourth part. In the last part the interaction between eddies and the west boundary current is discussed.Based on the analysis of the in situ observation data, the Sea Level Anomaly data from the Satellite Altimeter and the Sea Surface Temperature from the Satellite Spectroradiometer during the field experiment, the upper ocean velocity field during the field experiment is reproduced. By analysis of the Sea Level Anomaly, we find that 49 eddy shedding events happened from 1992.10 to 2005.5. Among 193 bouys which passed by the Luzon Strait only 8 drifted into the SCS when the northeast monsoon prevailed. We conclude that they were unlikely carried by a direct flow but were captured by the NWLCG when the Kuroshio took them there.It is found that the net transport in the Luzon Strait varies seasonally from 14.0Sv westward to 1.0Sv eastward. The annual mean net transport was 5.4Sv westward. Above 500m an obvious branch of the Kuroshio intruded in the SCS from winter to spring. And this branch disappeared from summer to fall. There exists permanent upwelling in the North SCS which is caused by the anticyclonic eddy due to the Kuroshio Intrusion. Numerical results also show that the inflow locates in the south of Luzon while the outflow locates in the north. The latitude of inflow and outflow varies seasonally.Numerical experiments show that the Mindoro Strait plays an important role in adjusting the balance of the Pacific and the SCS. While the wind over the Pacific basin controls the yearly mean transport of the Luzon Strait, the SCS monsoon has more effect on the seasonal variation of the Luzon Strait transport than the wind over the Pacific basin. The model resolution has a certain effect on the transport of Luzon Strait, but the trend that the net transport is westward during northeast monsoon is not changed.On the map of Sea Level Anomaly from the satellite altimeter we found eddies propagating westward in the ocean basin .When they met the Kuroshio, interactions were inevitable. It is found that with the existence of the cyclonic (cold) eddy at the east of the Kuroshio, its main axis tends to be attracted. And with the existence of the anticyclonic eddy, its main axis tends to deviate westward.A reduced-gravity primitive equation eddy resolving model is used to study the interaction of a typhoon-induced eddy and a wind-driven general circulation. Results show that eddies on both sides of the west boundary current (WBC) can affect the path of WBC. Especially when an anticyclonic eddy locates at the west of WBC, an eddy-shedding event is to happen.