北疆北部2次区域性暴雨的中尺度环境场分析

Analysis of Mesoscale Ambient Field of Two Heavy Rainstorms in Northern Xinjiang

利用常规资料、EC细网格和T639模式12 h预报场对2013年夏季发生在北疆北部的2次区域强降水过程中12 h最强降水时段的环境场进行中尺度分析。结果表明,中亚低槽北上强降水落区位于500和700 h Pa中尺度气旋的第一、四象限及对流层低层冷槽的右侧,850h Pa切变线附近,地面中尺度高压前部、边界线和切变线附近及干线西侧的重合区域。西西伯利亚低涡型暴雨位于中尺度短波槽前、高空西南急流出口区左侧辐散区,700和850 h Pa切变线西侧及干线西南部,850 h Pa偏西、偏东及东南3股气流汇合区,地面干线的西部、辐合线东部及切变线附近的重叠区域。中亚低槽北上暴雨天气为非典型暴雨易漏报。用模式12 h预报场制作高空综合图,可提高预报时效,EC细网格优于T639模式。

For forecasting the precipitation more than 24 mm in 12 hours, the model output ofprecipitation data, which sometimes have large deviation, is an important basis. Based on Mesoscaleanalysis technology, using conventional observation data, EC fine grid data and T639 model 12 hforecast field, the 12 h ambient field of mesoscale weather chart of two strongest rainfall period ofregional heavy rainfall episodes in North Xinjiang in summer of 2013 were analyzed. The resultsshow as follows. Caused by Central Asia trough going up to the north, the rainstorm located at theoverlap area of the first and fourth quadrant of mesoscale cyclone at 500 and 700 hPa, near theshear line on 850 hPa, at the mesoscale high pressure front,near the boundary line, the shear lineand at the west side of the dryline. The West Siberia Vortex Rainstorm was in front of the mesoscaleshort wave trough, at the divergence zone on the left of the southwest jet exit, at the west side of theshear line and to the southwest of the dryline at 700 and 850 hPa where the three air currents fromwest, east and southeast at 850hPa converged, and shear line of overlap area on surface. Therainstorm caused by Central Asia trough going up to north is an typical storm that is easy to beomitted. With 12 h forecast field from the model, the forecast for time can be improved and theaccuracy of EC fine mesh was better than that of T639 model.