Seasonal Variation Of The Luzon Strait Throughflow

The seasonal variability of wind stress and wind stress curl based on different datasets isanalyzed. It is found that there are three strong wind speed area and three weak wind speedarea in the South China Sea and its adjacent seas in winter, whereas weak wind speed centersin the southern and northern of the South China Sea and strong wind speed center in the eastof Indo-China Peninsula. The distribution of wind stress is strong in the northern but weak inthe southern of the South China Sea in spring and fall. The high value areas are located at theTaiwan Strait and the Luzon Strait, whereas the low value area is located along theKalimantan coastal. The wind stress curl distribution is negative in the northwestern of theSouth China Sea but positive in the southeastern of the South China Sea in January. In July,the distribution of wind stress is opposite with that of January.The Luzon Strait volume transports are calculated based on the island rule with threedifferent integral paths. The results show that the annual mean volume transport in the LuzonStrait is from the Pacific Ocean into the South China Sea. The transports change little withdifferent integral paths, which confirm that the selection of western segment is not critical tothe total transport discussed by Godfrey. When choose of western boundary integral path isoptional to facilitate the calculation of the path. The Luzon Strait volume transports, however,show different seasonal variability. The results of ASCAT and SODA data show that theLuzon Strait Throughflow is outward (from South China Sea to Pacific Ocean) in summer,but inflow in winter; while the results of the others (CERSAT, ERS-1, ERA-Interim andQuikSCAT data) show that the Luzon Strait water exchange is almost in flow all through theyear with its maximum transport in winter and followed by fall and spring.The vertical profile of zonal flow and zonal geostrophic flow along the120.75°E in theLuzon Strait based on the SODA dataset are analyzed to reveal the vertical structure of theLuzon Strait water exchange and its seasonal variability. It is found that the vertical structureof the zonal geostrophic flow is consistent with those of zonal flow. The annual meantransport of Luzon Strait water exchange is form the Pacific Ocean into the South China Sea, which is consistent with the estimation of the island rule. The seasonal variability of theLuzon Strait water exchange could be classified as three layers: in the upper300m, the zonalflow shows significant seasonal variability under the forcing of the Asian monsoon, in thelayer under300m, the zonal flow shows little seasonal variability.0-500m layer is centralinflow, both ends are outflow, main inflow;500-1500m layer substantially the South into theNorth out of the structure,2000m layer below the flow rate is small. The use of verticalintegration resulting zonal flow Luzon Strait water exchange volume transport andgeostrophic volume transport results are shown,0-100m layer there was a significant inflowsummer winter seasonal variation of the flow, and the winter large volume transport insummer.100-500m layer laminar annual inflow,500-800m annual outflow. According to thevertical distribution and volume transport variation can be concluded that the geostrophicbalance water exchange in the Luzon Strait maintain vertical structure and seasonal variationsplay an important role.