台海地区一次冬季冷锋降水过程的数值模拟

利用WRF中尺度模式,结合FY-2E卫星云图和常规气象资料,对台海地区一次冬季冷锋降水过程进行了数值模拟研究.结果表明:1)微物理方案对台海地区冬季冷锋降水过程的模拟具有敏感性,Milbrandt双参数微物理方案能较好地再现云系层次结构、冰相降水过程及其云系的对流发展,24 h累积降水量模拟结果优于其他微物理方案.2)锋区的降水粒子(雨水、雪晶和霰)混合比大于锋后,锋区雨带集中在地面锋线的中段,锋后雨带偏向冷区的西南段.3)锋区附近云系受低空急流及台湾岛中部高山地形抬升共同作用,在迎风坡形成强降水中心,对应空中霰含量高值区.4)低空高相当位温、强辐合、正涡度和对流性不稳定与高空强辐散和负涡度的配置是本次冷锋云系维持与发展的重要原因.

Numerical simulation of precipitation development associated with a wintertime cold front in Taiwan Strait

The precipitation process of a wintertime cold front in the Taiwan Strait was simulated based on the mesoscale model WRF,combined with FY-2E satellite image and the conventional observation data.Conclusions are as follows:1)The microphysics scheme is sensitive to the simulation of winter cold front in the Taiwan Strait,and Milbrandt double-moment microphysical scheme can successfully reproduce the hierarchy of cloud system,the ice-phase precipitation process and the convective development of clouds,which is more superior than other microphysical schemes for the simulations of 24 hours accumulated precipitation.2)The mixing ratio of precipitation particles(rain,snow and graupel) of frontal zone is larger than that of the post-frontal part.The rain band of frontal zone gathers in the middle of surface frontal line,and the post-frontal rain band is deflected to the southwest cold region.3)The near frontal zone clouds are influenced by the low-level jet stream and the orographic uplift in the middle of Taiwan Island,therefore it results in a strong precipitation center generating in the windward slope,which corresponds to the high content area of graupel in the air.4)High equivalent potential temperature,strong convergence,positive vorticity and convective instability at the lower level accompanied by strong divergence and negative vorticity at the higher level is the major reason for the maintenance and development of the cold frontal clouds.