青海东部农业区短时强降水要素特征分析

Characterization of Short-Term Heavy Precipitation Elements in Agricultural Areas of Eastern Qinghai

文章利用自动气象站的逐小时地面气象要素填图、FY-2和FY-4卫星云图资料、多普勒雷达资料对2016-2020年青海东部农业区短时强降水发生前和发生时的要素变化进行综合分析,结果如下:青海东部农业区短时强降水北多南少,多数发生于8月中下旬,其中午后至傍晚发生频率更高;短时强降水过程前具有升压、降温、增湿的特征,前1小时比前3小时的特征变化更明显;七成以上短时强降水发生时段从低到高各层垂直上升速度均为负值,另外地形辐合抬升对于降水有很大贡献;红外云图特征可分为椭圆状云团、带状云系、斜压叶状或逗点云系三类,降水强度与相当黑体亮温呈反比;短时强降水时段的强回波质心高度偏低,组合反射率、垂直液态水含量和回波顶高与降水量基本呈正比。分析结果可为未来青海东部农业区短时强降水的临近预报及预警提供参考依据。

Useing hour-by-hour ground meteorological element filling maps from automatic meteorological stations,FY-2 and FY-4 satellite nephogram data,and Doppler radar data,this paper conducted a comprehensive analysis of the elemental changes before and during the occurrence of short-term heavy precipitation in the agricultural area of eastern Qinghai from 2016 to 2020.The results are as follows:Short-term heavy precipitation in the agricultural area of eastern Qinghai was more in the north than in the south,mostly occurring in mid to late August,with the higher frequency of occurrence from late afternoon to late evening.The short-time heavy precipitation was characterized by the increase of pressure,temperature and humidity before the process,and the change of characteristics is more obvious in the first hour than in the first three hours.More than 70%of the short-time heavy precipitation occurs when the vertical velocity of each layer from low to high is negative,and the topographic convergence lift has a great contribution to precipitation.The characteristics of infrared nephogram can be divided into three categories:elliptical cloud cluster,band cloud system,oblique pressure leaf or comma cloud system,and the intensity of precipitation is inversely related to the Black Body Temperature.The height of the strong echo center of mass is low during the short-time heavy precipitation period,and the composite reflectivity,vert integrated Lilquid and echo tops are basically positively proportional to the precipitation amount.The analysis results can provide a reference basis for the proximity forecast and early warning of short-time heavy precipitation in the agricultural area of eastern Qinghai in the future.