中文摘要：

利用POM（Princeton Ocean Model）对吕宋海峡附近的环流情况进行数值模拟，结果表明，吕宋海峡净流量季节变化明显，除5月和6月为东向净流外，全年自7月至翌年4月皆为西向净流。7月至11月净流量由1．6Sv（1Sv=1×10^6m^3／s）持续增加至14Sv，12月至翌年4月净流量从13．8Sv持续减小至3．1sv。年平均值为5．7Sv。500m以上，秋、冬季有明显的黑潮分支进入南海，而在春、夏季黑湖南海分支消失或者较弱。在500m以下，黑潮位置由于北赤道流分岔位置的变化而发生南北移动，从而影响黑潮深层入侵南海。作者以保持与表层流速方向相一致的最大深度为界将流场分为上下两层，上层西向（入）流区域占据吕宋海峡南部、中部，秋、冬季范围最大，夏季向中部收缩，其深度空间分布呈东浅西深结构，在吕宋海峡入口处，入流深度呈南北浅中间深的结构。上层东向（出）流主要分布在海峡北部，夏季向南部扩展，范围最大。120．75°E断面除9月和10月外，下层净输运量与上层反方向。9月和10月上、下层净输运量皆为西向。上层年平均净流量为-7．6Sv（这里“-”表示净流量向西，下同），下层为1．8Sv。上层出入流深度随季节上下浮动范围可达数百米，海峡中部入、出流最深可达1800m。

英文摘要：

The Princeton Ocean Model （POM） was used to simulate the seasonal variation of water exchange in the Luzon Strait. The model domain covers the North Pacific（20°S-60°N, 100°E-70°W） with closed boundaries. A variable horizontal grid was set up with the finest grid of 0.25° in the South China Sea （SCS）. It is found that the Luzon Strait Transport （LST） has seasonal variations. Except for the eastward LST in May （1.0Sv） and June （0.9Sv）, westward LST dominates from July to the next April. The LST increases rapidly from July （1.6Sv） to November （14.0Sv）, and decreases from December （13.SSv） to the next April （3.1Sv）. In the depth above 500m, a clear branch of the Kuroshio intrudes the SCS from winter to spring; and this branch disappears from summer to fall. Below 500m, the Kuroshio affects the LST less significantly because the bifurcation latitude of the North Equatorial Current moves northward. Furthermore, we divided the velocity field of Luzon Strait into upper and lower layers at the depth at which the flow direction remains the same to the surface one. We called it the sign-changing depth. In the upper layer, the inflow of the northern SCS occupies the west and middle parts of the Luzon Strait, while the outflow （eastward）, the northern part. In autumn and winter the area of the inflow in the upper layer is the largest. In summer the area of the inflow contracts to the middle, while the area of the outflow extends southward. The sign-changing depth is shallower in the east, but deeper in the west. Considering the 120.75°E section in the Luzon Strait, in the upper layer, the direction of net LST is westward in almost all year except August with the maximum LST （16.2Sv） in December. In the lower layer however, the direction of the net LST is westward only from August to October. The annual mean net transport is -7.6Sv in the upper layer and 1.8 Sv in the lower layer （＂-＂ indicates the net LST is to the westward）. The sign-changing depth varies seasonal