山东一次连续性降雪过程云微物理参数数值模拟研究

A Numerical Simulation of Cloud Microphysics Parameters for Sustaining Snowfall in Shandong Province

利用PSU/NCARMM5V35非静力数值模式对2005年2月14—16日山东连续性降雪过程进行了数值预报,模拟的降雪开始时间、发展演变及持续时间与观测较一致。在成功模拟的基础上,用模式输出预报资料,特别是采用Reisner混合冰相过程计算的云水、雨水、冰晶、雪晶等比含水量数值,对降雪过程的水汽输送、不同发展阶段微物理参数的演变特征进行了分析。结果表明,来自南海的西南急流和低层的东南风水汽输送,850hPa中尺度切变线的维持和低涡的发生、发展,为暴雪的产生提供了宏观条件;模拟的运动场和微物理场的时空演变表明,垂直运动是水汽凝结、冻结和冰粒子碰并和“蒸-凝增长”的运动学条件。

To better understanding of the sustaining snowfall occurred in Shandong on 14- 16 February 2005, the PSU/NCAR MM5 model is used to replicate the process. The simulation results show that the start, evolvement and duration the event agree well with the observation although some shortage exist. On the basis of success simulation, the conditions of vapor and evolvement of cloud microphysics parameter in the process are analyzed with the model output data, especially the quality content of ice （Qi）, graupel （Qg）, snow （Qs）, cloud water （Qc） and rain water （Qr） calculated with Reisner graupel scheme. The results show that the sustaining snowfall is based on the vapor supply from SW and SE winds, the development and evolution of the shear-line and intermediate cyclone on 850hPa. The simulated velocity and cloud microphysics fields show that vertical motion is dynamics factor causing the vapor condensation and freezing, and ice particle increase. The opportunity of artificial seeding in different condition is also discussed.