摘要:本文以GFS资料为初始场，利用WRF（v3.6.1）模式对2015年第22号台风“彩虹”进行了数值研究。采用CMA（中国气象局）台风最佳路径、MTSAT卫星、自动站降水为观测资料，对比了4个微物理方案（Lin、WSM6、GCE和Morrison）对“彩虹”台风路径、强度、结构、降水的模拟性能。模拟发现上述4个云微物理方案都能较好地模拟出“彩虹”台风西行登陆过程，但是其模拟的台风强度、结构及降水存在较大差异；就水成物而言，除GCE方案对雨水的模拟偏高以外，其他方案对云水、雨水过程的模拟较为接近，其差异主要存在于云冰、雪、霰粒子的模拟上。本文对比分析了WSM6和Morrison两个方案模拟的云微物理过程，发现WSM6方案模拟的雪和霰粒子融化过程显著强于Morrison方案，但是冰相粒子间转化过程的强度明显弱于Morrison方案。云微物理过程的热量收支分析表明：WSM6方案模拟的眼区潜热更强，暖心结构更为显著，台风中心气压更低。细致的云微物理转化分析表明，此次台风降水的主要云微物理过程是水汽凝结成云水和凝华为云冰；生成的云水一方面被雨水收集碰并直接转化为雨水，另一方面先被雪粒子碰并收集转化为霰，然后霰粒子融化成雨水；而生成的云冰则通过碰并增长转化为雪。小部分雪粒子通过碰并收集过冷水滴并淞附增长为霰粒子，随后融化为雨水，大部分雪粒子则直接融化形成地面降水。
关键词:台风降水/
云微物理过程/
数值模拟/
“彩虹”台风
Abstract:Using GFS (Global Forecast System) data as the initial field, numerical simulations of typhoon Mujigae in 2015 were conducted using the WRF3.6.1 (Weather Research and Forecasting Model). A comparative study of four microphysical schemes (Lin, WSM6, GCE, and Morrison) with concerns of the simulated typhoon track, intensity, precipitation, and contents of hydrometeors were carried out using the best track dataset from CMA (China Meteorological Administration), MTSAT satellite data, and precipitation data collected at automatic weather stations. It is found that all the four cloud microphysical schemes can well simulate the westward movement and landfall of the typhoon. However, the simulated typhoon intensity, structure, and precipitation are quite different using the four different cloud microphysics schemes. In terms of the water content, precipitation is overestimated by the GCE scheme, while the other three schemes yield similar simulations of cloud water and rain. This result indicates that the differences among the schemes mainly exist in the simulation of cloud ice, snow, and graupel particles. Comparing the cloud physical transformation processes simulated by the WSM6 and Morrison scheme, it is found that the simulation of melting snow and graupel particles by the WSM6 scheme is better than that by the Morrison scheme, whereas the simulated strength of the conversion process between ice phase particles is weaker than that by the Morrison. The heat budget analysis for cloud microphysical process shows that strong diabatic heating is more concentrated over the eye area in the WSM6 scheme, which results in stronger warm core structure and lower central pressure than in other schemes. Detailed analysis of cloud microphysical conversion shows that the main cloud microphysics process involved in typhoon precipitation is the condensation and/or sublimation of water vapor into cloud water and/or cloud ice. The cloud water is then partly accreted directly into rainwater, and partly accreted by snow particles and form graupels, which finally become rainwater as the graupel particles descend to the melting layer. Through accretion, the cloud ice is converted into snow, while part of the snow particles collect super-cooled water droplets and rim into graupels, which then melt into rain. A considerable part of snow particles directly melt to form precipitation.
Key words:Typhoon rainfall/
Cloud microphysical process/
Numerical simulation/
Typhoon Mujigae
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