2003年春季江淮一次暴雪过程的模拟研究

Numerical Simulation on a Snowstorm in Changjiang-Huaihe River Basin in Spring 2003

采用NCEP全球再分析资料和常规地面、高空观测资料,利用非静力中尺度数值模式MM5(V3.6)对2003年2月江淮地区暴雪过程进行了数值模拟。结果表明,MM5能够较好地模拟出地面及中低空大、中尺度环流系统,能够成功模拟出暴雪中尺度低涡的发生、发展及结构演变;低空西南急流与暴雪有着密切关系,对暴雪天气预报有很好的指导作用;对涡度场、散度场和垂直速度场的诊断表明,运动场和热力场的相互配置及耦合关系非常有利于暴雪切变线的发展及暴雪形成与维持。还利用模拟雷达反射率因子检验了模拟的正确性。对温度场的分析可知,降水性质与700 hPa、850 hPa温度平流有直接关系。

Based on the NCEP/NCAR reanalysis and other observational datasets,the nonhydrostastic mesoscale model MM5（V3.6） is used to simulate a snowstorm occurred in Changjiang-Huaihe river basin during February 2003. Comparison between results of numerical simulation and objective analysis shows that the MM5 can replicate the large-scale and mesoscale circulation systems. The results of numerical simulation indicate that the MM5 can successfully simulate the genesis, development and structural evolution of the snowstorm＇ s mesoscale vortex. The analysis of low-level jet shows that the low-level Southwest jet has close relationship with snowstorm,and can guide the snowstorm accurately. The diagnoses of crosssections on vorticity field,divergence field and vertical velocity field show that the allocation and coupling between motion field and thermal dynamic field could create a favorable condition for the development of snowstorm shear line and the formation and maintenance of the snowstorm. The simulation of radar reflectivity factor indicates that the simulated snowstorm＇ s precipitation distribution and intensity are reasonable. The analysis of temperature shows that the feature of precipitation is directly related to the temperature advection on 700 hPa and 850 hPa.