汕尾外侧冷水跨陆架输送的形成机制

The Mechanism of Cold Water Cross-shelf Transport in the Continental Shelf Off Shanwei

采用三维斜压非线性海洋模型(regional ocean modeling system,ROMS),设计1个标准模式和2个理想实验,研究汕尾外侧冷水跨陆架输送的影响因子并估算其量值.标准模式中汕尾外侧存在高密冷水团在陆坡处涌升并向内部陆架输运,且在等深线向岸辐聚凸起(等深线曲率变化显著)区域跨等深线运动最强.理想实验说明影响汕尾外侧冷水跨陆架输送的影响因子主要是对流和底部Ekman作用.采用理论公式分别估算对流和底部Ekman作用产生的跨陆架流速,结果显示等深线辐聚凸起区域的跨陆架输送受对流和底部Ekman作用共同控制,且对流的作用更大;等深线变化平缓区域的跨陆架运动主要受底部Ekman作用的影响.

The mechanism of bottom cold water cross shelf transport in the coastal shelf off Shanwei was investigated with the use of the regional oceanic modeling system （ROMS）, by designing a control run and two numerical tests. The first numerical test is closing the advection term and other parameters are the same with control run. The second numerical test is reducing the local bottom stress which is based on the control run. The control case shows that there is a high density,cold water mass flows from the outer shelf to the inner shelf in the coastal shelf off Shanwei. The stronger cross-shelf transport exists in the region with isobaths convex onshore. The results of the numerical tests suggest that the main factors which cause cross shelf transport are the advection term and the bot tom Ekman effect. Then two formulas are applied to estimate the cross-shelf velocities which are induced by the advection and the bottom Ekman effect, respectively. The results show that in the region with isobaths convex onshore,the cross shelf transport is con-trolled both by the advection and bottom Ekman effect,and the advection term is more important. The cross-shelf transport in the re- gion with smoother isobaths is mainly controlled by the bottom Ekman effect.