台风“森拉克”的数值模拟研究:海洋飞沫的作用

NUMERICAL SIMULATION OF TYPHOON "SINLAKU":ROLES OF SEA SPRAY

台风作为一种在海洋上生成和演变的强烈天气现象,除了环境流场、自身结构以及地形等因子对它产生影响外,海气间的热量动量交换也是台风演变过程中不可或缺的因子。台风期间在海气界面生成大量海洋飞沫,这些飞沫在台风边界层的蒸发必然对海气之间的通量传输过程产生影响,进而影响到台风本身的演变。文章将海洋飞沫参数化引入大气中尺度模式中,对2002年16号台风“森拉克”的演变进行了数值模拟研究。结果表明,引入海洋飞沫参数化方案,可使台风期间海气界面的潜热通量增加50%,10m层风速最大值增加30%,从而使模拟台风的强度明显增加,使模拟结果更趋于合理。因此,在台风数值模拟和预报中考虑海洋飞沫的作用是十分必要的。

It has long been recognized that the evolution of the western Pacific typhoons may be strongly affected by large-scale circulations, asymmetric structure of typhoons themselves and terrain, etc. However, the roles of flux transfer processes at the air-sea interface have remained unclear. High winds of typhoons can generale large amounts of spray. Through the evaporation of spray droplets, the air-sea fluxes may be significant-ly modified, which can, in turn, affect the evolution process of typhoons. In this paper, a recent western Pacific typhoon in 2002, typhoon 'Sinlaku', is simulated using a cou-pled atmosphere-sea spray modeling system. It is found that, 1) sea spray can cause a significant latent heat flux increase up to 50% of the interfacial fluxes in typhoon 'Sinlaku'; 2) taking into account the effects of sea spray, the intensity of a modeled typhoon can increase significantly, by 30% in wind speed at 10m, which may much im-prove the estimate of maximum storm intensity in the atmospheric model; and 3) the effects of sea spray mainly focus on the high wind regions around the storm center and are mainly felt in the lower part of troposphere.