【摘要】 利用宁夏区域自动站逐小时降水量资料、NCEP 2.5°×2.5°间隔6 h再分析资料、探空资料、多普勒雷达资料及FY-2G静止卫星逐小时红外亮温(TBB)资料,对2015年6月22日白天到夜间出现在宁夏六盘山地区的一次区域性暴雨天气过程进行诊断分析。结果表明:(1)北槽南涡是本次局地暴雨过程的大尺度环流背景。(2)正涡度使气旋式环流加强,加大了暴雨区辐合上升运动。低层辐合高层辐散,有利于强降水的发生、发展和维持。暴雨区上空整层相对湿度在80%以上,700 hPa比湿超过9.8 g/kg,500 hPa比湿大于4.4 g/kg,并长时间维持可作为此次暴雨过程的水汽条件指标。(3)垂直速度形成的南北经向次级环流增强了泾源南侧中低层暖湿空气的辐合抬升,同时加大了其北侧高层大气下沉运动产生的抽吸作用,形成正反馈,造成降水强度增强,最终形成暴雨。700 hPa垂直速度小于-0.157 Pa/s是此次暴雨过程动力抬升条件的重要指标。(4)本次暴雨过程以混合性降水为主,对流发展不旺盛。最大降水时段不是出现在TBB最低的时间而是出现在TBB增幅最大的时间,且TBB增幅越大降水量越大。TBB在-50℃以下,且TBB梯度达15℃以上区域与暴雨区有较好对应关系。更多还原

【Abstract】 Based on the automatic station precipitation data in Ningxia, the NCEP reanalysis data, sounding data, Doppler Radar Data and the TBB data of FY-2 G, the diagnostic analysis of torrential rain process in the Mountain of Liupanshan in Ningxia occurred on June 22, 2015 was carried out. The obtained results are as follows:(1)The trough in north and a vortex in south is the large-scale circulation background of this precipitation process.(2)The positive vorticity strengthens the cyclonic circulation, and the convergence ascending over the heavy rain area has been enhanced. The structure of low-er-level convergence and upper-level divergence is beneficial to the genesis, development and maintaining of heavy rainfall.The rainstorm vapor index is that the relative humidity above the rainfall area maintains more than 80%, the specific humidity at 700 hPa is more than 9.8 g/kg, and the specific humidity at 500 hPa is more than 4.4 g/kg.(3)The secondary circulation of south-north meridian has been made by the vertical velocity which leads to the convergence and ascending of the warm and moisture air at low layer in the southern of Jingyuan. The sinking motion in the northern of Jingyuan makes the pumping action. All these factors forms a positive feedback and increases the precipitation, inducing the rainstorm finally. The rainstorm dynamic lifting index is that the vertical velocity of 700 hPa is less than-0.157 Pa/s.(4)The heavy rainfall is mainly mixed precipitation, and the convective development is not strong. In addition, the maximum precipitation area is not appeared at the minimum TBB but at the maximum increasing amplitude point. The precipitation is proportional to the increase of the TBB amplitude. A good correspondence has been found between the heavy rain area and the regional when the TBB is below 50 ℃ and over 15 ℃ of gradient.更多还原