北部湾潮致、风生和热盐余流的三维数值计算

THREE-DIMENSIONAL NUMERICAL SIMULATION OF TIDE-INDUCED,WIND-DRIVEN AND THERMOHALINE RESIDUAL CURRENTS IN THE BEIBU BAY

基于二阶湍流闭合模型计算涡动粘性系数的POM三维水动力模式 ,研究采用细网格 ,考虑了 6个岛屿的影响 ,海底摩擦系数进行划片取值 ,把作为强迫力的潮汐、风力和热盐统一在一个模型中 ,诊断计算并获得了北部湾三维潮致 -风生 -热盐余流。用实测资料对计算结果进行了验证 ,显示了本研究结果的合理性。同时给出了潮致余流、风生流和热盐余流 ,并且对各因子的作用做了比较和分析 。

By means of a three-dimensional POM model,which com pu tes the eddy viscosity coefficient based on a two-order turbulent closure model ,three-dimensional tide-induced residual currents,the wind-driven and thermoh aline currents in the Beibu Bay are diagnostically computed with a thin grid. Th e tide,wind and thermohaline as the forcing items are unified into the model. I n the computation,the effects of 6 islands are considered and different bottom f r iction coefficients are taken according to the difference of the sea region. The results are verified with the measured data and display reasonableness. The eff ects of every factor on the tide-induced,the wind-driven and thermohaline curr ents are compared and analysed. The results show that:(1) wind-driven currents dominate in the Beibu Bay residual currents,ever the thermohaline currents and t ide-induced residual currents,(this relation is more apparent,especially in win ter);and (2) the most apparent feature of the summer thermohaline currents in th e Beibu Bay is that the stronger counter-clockwise circulation exists in the su rface and mediate layers (Its existence plays an important role in the maintenan ce of the cold water mass in the Beibu Bay in both spring and summer)