2011年7月黑龙江省西部罕见暴雨成因分析

利用区域自动站和常规观测资料及卫星云图、多普勒雷达资料，对2011年7月31日黑龙江省西部大区域暴雨过程进行分析。结果表明：黑龙江省西部暴雨区位于高空西风急流出口区左侧、低空和超低空急流的左侧，高空辐散和低空辐合作用为暴雨过程提供了动力条件，低空和超低空急流为暴雨提供了水汽条件；在对流层中层有较强的干冷空气侵入，短时强降水落区位于干侵入边界，并且与TBB大梯度区有较好的对应关系；而在雷达回波中，短时强降水落区位于速度图中的风场不连续线附近。

Forming reason of a rare rainstorm on July of 2011 in the west of Heilongjiang province

Based on the data from the automatic weather stations, the conventional observation data, the data from the satellite cloud imagery and the Doppler radar, a rainstorm process on July 31,2011 in the west of Heilongjiang province was analyzed synthetically. The results show that the rainstorm falling areas are located in the left side of the upper-level westerly jet exit region and the ultral-low-level jet. The upper divergence and lower convergence, the low-level and ultra-low-level jets provide the dynamic conditions and the water vapor conditions for this process, respectively. The strong dry cold air invades in the middle level of troposphere. The falling area of short-time rainstorm is located in the dry intrusion boundary of the strong cold air in the middle level, and it has a very good corresponding relation with the TBB region of big grads. However, it is near the discontinuity line of wind field on the radar echo velocity chart.