“一一·二四”海难渤海风场的数值模拟

Wind field numerical simulation for a great shipwreck in Bohai Sea on November 24, 1999

用中尺度数值模式 ＭＭ５对 １９９９年 １１月 ２４日烟台附近发生重大海难事故的渤海风场进行了数值模 拟，探讨了该次冷锋大风的风场特征和影响机制．结果表明：用９０ｋｍ的粗网格可以成功地模拟地面冷高压 与锋面的发展和移动，以及高空环流形势的演变．而通过３０ｋｍ细网格的模拟发现，在冷锋后的行星边界层 中．存在着一条宽度为 ２００ ｋｉｎ的中尺度强风带，最大风速位于 ９２５ｈＰａ，它与高空的极锋急流并不相连；细 网格还模拟出了渤海中尺度低压的发展过程，它使近地面层大风的强度显著加强．模拟还表明，海陆差异对 近地面的风场分布有重要的影响，强风带移入渤海后，在渤海海域形成一个 ２００—３００ ｋｍ的中尺度强风 区．因此，采用具有较高分辨率的中尺度数值模式，对提高渤海大风的预报水平，避兔海难事故的发生更具 有重要意义．

Appling the Penn/NCAR mesoscale model (MM5). this paper simulates the wind field of Bohai Sea in which a great shipwreck happened on Noember 24. 1999. The results of 90-km coarse-grid show that MM5 has a good ability to reproduce the evolution of the synoptic scale situation of the cold wave process. The 30-km fine-grid results indicate that, there was a 200 km wide mesoscale strong wind belt in the planetary boundary layer behind the cold front. The maximum wind speed layer located at the 925 hPa. which was not connected with upper level polar-front jet. Fine-grid results also succeeded in showing the mesoscale development of low in the Bohai Sea, which led to increase the intensity of wind speed in the lower atmosphere layers considerably. The simulation also reveals that land-sea contrast has an important effect on the distribution of the wind field at the surface layer. When the strong wind band moved into the Bohai Sea, the wind speed increased considerably and a 200 - 300km wide mesoscale strong wind region formed in the Bohai Sea. Therefore, the high-resolution mesoscale model MM5 is helpful to improve the strong wind forecast caused by the cold wave in winter, which is redound to avoid great shipwreck to happen again.