渤海悬浮颗粒物三维输运模式的研究 Ⅱ.模拟结果

3D SUSPENDED PARTICULATE MATTER TRANSPORTATION MODEL IN THE BOHAI SEA Ⅱ.SIMULATION RESULTS

利用本文I给出的悬浮物输运的三维动力数值模式，在渤海中进行了两种情形下的模拟。首先模拟了黄河排出的细颗粒物在渤海中的运动，结果表明，这些颗粒物大部分将滞留在渤海内，而且其分布与气象条件有密切关系。另外对大风情况下悬浮物的输运进行了模拟，结果显示，大风到来时海水中的悬浮物浓度急剧上升，海底侵蚀增强，而风停止时，悬浮物浓度经过一段时间延迟后，会恢复到正常状态。这与实际观测的趋势是一致的，表明用本模式研究悬浮物的输运是可行的。

In this paper the model described in the former ar ticle is used to simulate SPM transport. The space resolution is 1/12 degree bot h in the latitude and in longitude in the horizontal direction and 10 layers is divided in the vertical direction. The whole system is driven by the meteorological force such as wind stress and air pressure in 1982. The tidal wave propagati ng from the Bohai Strait and the Huanghe River inflow are the other two driving forces. Two cases have been studied in this paper. The first one is numerical tracing of sediment particles discharged from the Huanghe River. 100 particles are release d from the Huanghe River mouth on January 4, April 1 and July 1 in 3 separate ru ns. After the release, these 100 particles are traced and the distribution patte rns at different months are shown. It is found that almost all the particles sta y in the Bohai Sea, but the positions of the SPM are not the same at the end of the simulation if they have different releasing time. The differences are from t he unique feature of the wind field for each month. The other one simulates SPM transport during strong winds. The results show that the SPM concentration in the water column increases rapidly when the wind gets strong. The erosion begins at the same time and the fine fraction of the sedimen ts becomes less than before. When the wind calms down the SPM in the water begin to settle on the seabed, but the concentration decrease slowly. Because the SPM is stirred up by the wind and distributed evenly, it needs some time to settle down. The vertical profile of the SPM concentration also changes significantly during the strong wind. Normally the SPM concentration is higher near the bottom than a t the surface. In the strong wind the SPM concentration at the bottom will incre ase quickly and the high concentration area goes up to the surface until the SPM concentration is nearly uniform. Then the SPM settle down slowly after the wind ceases. This reflects that the wind is essential to SPM transport in the sea.