海洋混合层厚度对热带气旋结构和强度变化影响的数值试验

Numerical Experiments of the Effect of Oceanic Mixing Layer Depth on TC Structure and Intensity Changes

利用高分辨率大气模式WRF(Weather Research Forecast)耦合了简单的海洋混合层模式,设计了不同海洋初始混合层厚度条件下的数值试验,研究了不同混合层厚度对热带气旋(TC)结构和强度的影响。结果表明,当TC经过海洋混合层厚度较浅海域时,TC对应的海洋底层的冷水更易上翻,最冷中心区出现在TC大风中心右后方160～240km处,海表面温度最大降温值可达-7℃,使其右后方的总表面热量通量交换显著减少,导致TC强度显著变弱;海洋冷却作用还会增强TC结构的非对称性,这与海洋冷却作用的非对称造成TC在边界层附近的涡度和散度平流分布不均密切相关。

The effect of the oceanic mixing layer depth on the tropical cyclone（TC） structure and intensity changes is investigated by using three sensitivity experiments,coupled the high resolution and non-hydrostatic idealized WRF model with a simple one-dimensional oceanic mixing layer model.The results show that,when the TC passes the region with a thin oceanic mixing layer,the surface heat flux is mainly reduced by the oceanic upwelling in the rear-right quadrant of TC center region with the sea surface temperature up to-7 ℃,is occurred in the rear-right of 160~240 km of TC maximum wind center,which is also leading to the increasing of TC asymmetric structure and the decreasing in TC intensity.And it is also found that the TC asymmetric structure is closely related to the distribution of the vorticity and divergence advection from oceanic cooling in the boundary layer of TC.