拖曳系数参数化方案对工程台风模拟风场的影响研究

基于台风边界层的最新观测和研究成果，提出了最大风速半径、边界层风速比、拖曳系数等关键参数的经验方案，并依据垂直平均水平运动方程，建立适用于西北太平洋的工程台风风场模型，最高分辨率为2 km。通过理想试验，验证了所建模型的合理性，并重点关注模拟风场对拖曳系数参数化方案的敏感性。结果表明，不同拖曳系数参数化方案（增长型、饱和型、下降型）对强台风内核区的风场模拟有显著影响，但对最大风速的模拟影响不大。为验证所建模型对实际西北太平洋台风的适用性，选取台风“海葵”（1211）进行个例试验，得到最大风速的平均误差为-0.36 m/s，均方根误差为2.22 m/s。进一步选取我国沿海6个受“海葵”影响的测站，进行模拟风向、风速与观测的对比分析，发现所建台风风场模型能很好地模拟出台风影响过程中的风向转变，但各测站的风速均方根误差在1.61~6.92 m/s之间。较大的风速误差主要出现在位于台风中心附近的测站，意味着我国沿海复杂地形对台风的衰减作用在模型中考虑不足，是未来的改进方向。 

EFFECTS OF THE PARAMETERIZATION SCHEME OF DRAG COEFFICIENT ON THE SIMULATION OF TYPHOON WIND FIELD IN ENGINEERING APPLICATIONA

Based on the vertically average equation of motion in the boundary layer, a typhoon wind field model is established for engineering application. A four-level nest grid system is used with the highest resolution being 2 km. The expressions of the radius of maximum wind speed, the wind speed ratio and the surface drag coefficient (C_D) are specified based on the observation and research findings of the typhoon boundary layer over the past decade. An idealized experiment is performed to verify the rationality of the model, and special attention is paid to the sensitivity of the wind field to the parameterization schemes of C_D. Results show that the change in C_D mainly affects the wind field in the inner core region of strong typhoons. but has no significant impact on the maximum wind speeds. Typhoon Haikui (No.1211) is then simulated in order to verify the applicability of the model to the typhoon in the western North Pacific region. The mean error of the maximum wind speeds is just -0.36 m/s, and the root mean square error (RMSE) is 2.22 m/s. The model can also simulate quite well the changes in wind directions of six meteorological stations in the East China when affected by Haikui. The RMSE of wind speeds is between 1.61 m/s and 6.92 m/s. Large errors appear at the stations near the center of typhoon, implying that the model dose not take adequate consideration to the complex terrain of East China, and needs further improvement in the future.