宁夏六盘山地区一次局地暴雨天气过程诊断分析
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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。
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.
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.
引文
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[3]赵庆云,张武,王式功,等.西北地区东部干旱半干旱区极端降水事件的变化[J].中国沙漠,2006,25(6):904-909.
[4]孔期,郑永光,陈春艳.乌鲁木齐7·17暴雨的天气尺度与中尺度特征[J].应用气象学报,2011,22(1):12-22.
[5]纪晓玲,贾宏元,沈跃琴.2002年6月7—8日宁夏区域性暴雨天气过程分析[J].干旱气象,2004,22(2):17-22.
[6]贾宏元,穆建华,孔维娜.2004年宁夏一次区域性大到暴雨的诊断分析[J].干旱气象,2005,23(2):24-29.
[7]刘建文,郭虎,李耀东,等.天气分析预报物理量计算基础[M].北京:气象出版社,2005:39-40.
[8]朱乾根,林锦瑞,寿绍文,等.天气学原理和方法[M].北京:高等教育出版社,2000:463-464.
[9]张天峰,王位泰,吴爱敏,等.庆阳一次强暴雨天气过程雷达回波特征[J].干旱气象,2007,25(3):61-65.
[10]陈渭民.卫星气象学[M].北京:气象出版社,2003:260-270.
[11]张驹,王敏,顾清源.四川2006年“9·3”暴雨过程中TBB与强降水对应关系分析[J].四川气象,2007,27(2):7-10.
[2]邵建,裴晓蓉,刘娟,等.近53 a宁夏暴雨时空分布特征[J].干旱气象,2015,33(4):595-601.
[3]赵庆云,张武,王式功,等.西北地区东部干旱半干旱区极端降水事件的变化[J].中国沙漠,2006,25(6):904-909.
[4]孔期,郑永光,陈春艳.乌鲁木齐7·17暴雨的天气尺度与中尺度特征[J].应用气象学报,2011,22(1):12-22.
[5]纪晓玲,贾宏元,沈跃琴.2002年6月7—8日宁夏区域性暴雨天气过程分析[J].干旱气象,2004,22(2):17-22.
[6]贾宏元,穆建华,孔维娜.2004年宁夏一次区域性大到暴雨的诊断分析[J].干旱气象,2005,23(2):24-29.
[7]刘建文,郭虎,李耀东,等.天气分析预报物理量计算基础[M].北京:气象出版社,2005:39-40.
[8]朱乾根,林锦瑞,寿绍文,等.天气学原理和方法[M].北京:高等教育出版社,2000:463-464.
[9]张天峰,王位泰,吴爱敏,等.庆阳一次强暴雨天气过程雷达回波特征[J].干旱气象,2007,25(3):61-65.
[10]陈渭民.卫星气象学[M].北京:气象出版社,2003:260-270.
[11]张驹,王敏,顾清源.四川2006年“9·3”暴雨过程中TBB与强降水对应关系分析[J].四川气象,2007,27(2):7-10.