【摘要】 利用卫星云图、多普勒天气雷达资料、常规观测资料和MM5模式模拟结果,分析了2005年12月4日典型冷涡造成山东半岛暴雪的云带变化、对流单体的生成与发展、低空急流特征及雷达强回波带的变化特征。结果表明:冬季冷涡携带强冷空气南下,经过渤海暖湿下垫面后影响山东半岛时,卫星云图上从渤海到山东半岛可以清楚地分析出造成暴雪的西南—东北向结构特征的横向云带;雷达图上,在渤海到山东半岛形成一强降雪回波带,PPI径向速度图上可清楚地分析出暴雪区的低空急流和中尺度对流的低空辐合,雷达径向速度垂直剖面反映暴雪产生在零速度线附近和低空急流的存在;MM5模式模拟结果显示:暴雪发生时山东半岛在1.5 km存在低空急流,水平风的时间—高度垂直剖面反映暴雪发生时干冷空气经过暖湿的渤海海面在700 hPa以下出现暖平流,垂直上升运动和散度的低层辐合、高层辐散与雷达图像反映的强降雪回波是相对应的。更多还原

【Abstract】 The analysis of observational structure characteristics of cold-air convective cloud and wind of heavy snow events of the typical cold vortex occurred in Shandong Peninsula on 4 December 2005 is undertaken using the satellite VIS image data,Doppler radar data and observational station data.Meanwhile,the numerical simulation is performed to be tested with the real observational data.The results show when outbreaks of winter cold air occur from the Eurasian Continent,snow cloud develop over the Bohai sea.The FY-2C VIS satellite image shows the cloud streaks which the alignment of SW to NE is almost perpendicular to the northwesterly wind in the lower troposphere.Doppler radar data show that the reflectivity of heavy snow at 0.5 elevation of the snowband extended from Bohai sea toward to Shandong Peninsula is about 30 to 40 dBz.In the velocity field,the anticlockwise movement of wind with height presented cold air current and a wind convergence in the low-level is studied by analyzing the Doppler radar data also.Velocity cross-section indicates the relationship between the wind velocity and snowstorms.The numerical simulated results display that there is a low-level jet at 1.5 km heights when heavy snow events occur in Shandong Peninsula.The time-height cross-section of horizontal wind above Weihai shows that there is warm air current from 1000 to 700 hPa.The changes of numerical simulated vertical velocity and divergence are in better agreement with observational data.The updrafts and the convergence in the lower layer are the dynamic mechanism of the snowstorms by analyzing the time-height cross-section of vertical velocity and horizontal divergence.更多还原