摘要
利用卫星、多普勒雷达、区域自动站、闪电定位等遥感资料和常规气象资料,对2012-07-29夜间宁夏平原大暴雨过程的中小尺度特征进行了分析.结果表明,造成大暴雨的天气系统主要是200 hPa 急流、500 hPa 短波槽、700 hPa低涡、850 hPa辐合切变,宁夏上游地区中低层存在一明显的辐合带、高湿区和多低值系统；卫星云图上中尺度对流云团快速发展并东移影响宁夏造成暴雨,强降水阶段云团平均亮度温度达220 K,最低亮度温度达210 K,亮度温度低于220 K的云团面积达到20000 km2；闪电时空分布特征与强降水高度一致,表明中小尺度强对流是造成暴雨的主要原因；雷达反射率图上多个强对流单体先后影响,出现明显“列车效应”,单体基本反射率和组合反射率在分别达到40-60,50-60 dBz,40 dBz的强回波高度突破了0℃层高度,同时3 km高度还存在大于50 dBz的强反射率因子核心；强降水阶段,径向速度图上伴有多个“逆风区”和风速辐合区,垂直方向径向速度正负相间分布；雷达回波顶高度和垂直累积液态水含量在强降水阶段分别达到8-11 km和10-30 kg/m2.
With remote sensing data and conventional meteorological data from satellite,Doppler radar, regional automatic station and lightening positioning,the author of this article analyzes the meso-and-micro-scale features of Ningxia plain’s extreme rainstorm on the night of July 29th,2012.The result shows that the weather system which caused the rainstorm were mainly 200 hPa jet stream,500 hPa short wave troughs,700 hPa vortex,and 850 hPa velocity convergence windshear,and there were obvious convergence belt,high humidity area and multi low value system in the middle-low layers of Ningxia upper stream areas;From the satellite cloud pictures,we can see that meso-scale convective cloud cluster rapidly expands and moves eastwards to create rainstorm.The average brightness temperature of cloud cluster during the heavy rain was 220 K,and the minimum brightness temperature was 210 K.The clouds area with brightness temperature less than 220 K was about 20 000 km2 .The highly consistency between lightening spatial and temporal distribution feature and heavy rainfall shows that meso-and-micro-scale severe convection is the primary cause of heavy rain.On the drawing of radar reflectivity diagram,there appears obvious “train effect”after the influences of several individual severe convections.The strong echo height of 40 dBz breaks the 0 ℃ layer height when individual base reflectivity and combination reflectivity reaches 40-50 dB and 50-60 dBz respectively,and the core of strong reflectivity factor larger than 50 dBz exists at the height of 3 km.The radial velocity diagram shows several “upwind areas”and “wind speed convergence zones”during the heavy rain, and the radial velocity of vertical direction alternative distributed by positive and negative speeds.The top height of radar echo and vertically accumulated liquid water content reaches 8-11 km and 10-30 kg/m2 respectively.
出处
《宁夏大学学报（自然科学版）》
CAS
2014年第4期380-387,共8页
Journal of Ningxia University(Natural Science Edition)
基金
中国气象局新技术集成基金资助项目(CMAGJ2013M58)
宁夏自然科学基金资助项目(NZ11248)
