Research Of Currents In The South China Sea Based On Satellite Altimetry And Satellite Remote Sensing Sea Surface Temperature

Due to its special geographical location and semi-closed geographic features,and the South China Sea is affected by the East Asian monsoon.The changes of Sea surface and sea surface temperature are large.Therefore,the South China Sea is characterized by complex flow systems,numerous vortices,and its research value is very high.The sea surface currents and mesoscale eddies in the South China Sea have been hotspots both at home and abroad since their discovery.In this paper,firstly,based on satellite remote sensing sea surface data,the optical flow of the South China Sea is extracted using the Hon-Schunck optical flow method.Using the sea surface level anomaly data to extract the geostrophic flow in the South China Sea based on the geostrophic balance.The reliability of the optical flow method in extracting sea surface currents over the South China Sea is proved.Then,based on these two kinds of datas,vector geometries were used to study the mesoscale vortices in the South China Sea,and the spatial-temporal distribution of mesoscale vortices in the South China Sea was statistically analyzed.The sea surface currents in the South China Sea were extracted based on the Horn-Schunck optical flow method.Sea surface temperature data have high spatial resolution.Compared with satellite altimetry data,it is possible to monitor seawater movement in a small area,which plays an important role in the further analysis of sea surface currents in the South China Sea.The Hom-Schunck optical flow method was used to extract the optical flow from the continuous sea surface temperature image sequences.By analyzing the relationship between optical flow and geostrophic flow,optical flow and SLA contours,geostrophic flow and SST images,found that the geostrophic flow and the optical flow have the same direction in a small area,and the vortices are monitored in different motion modes.In addition,the direction of the geostrophic flow is parallel to the SST temperature zone.And the collision line of the optical flow coincides with the contours of the SLA.Mesoscale eddies in the South China Sea were extracted based on vector geometric method.Due to the high spatial resolution of sea surface temperature data,a greater number of eddies can be monitored relative to satellite altimeter data,which is of great importance for further analysis of the mesoscale eddies in the South China Sea.However,using the sea surface temperature data to track the eddies is instable.Moreover,eddies have a small volume,and a short life span of approximately 7.8 days,while using the SLA data to track eddies is relatively stable and the vortex life is longer,averaging about 14.1 days.Because the South China Sea is located near the equator,the temperature is relatively high,and by the terrain and other factors,the sea surface temperature changes greatly by the day.Therefore,combining the two kinds of datas to extract the mesoscale vortices can more deeply understand the temporal and spatial distribution traits of the mesoscale vortices in the South China Sea.