风廓线雷达在一次大到暴雪天气过程中的应用

利用芜湖市边界层风廓线雷达资料对2012-12-29芜湖市出现的1次大到暴雪天气过程进行分析,结果表明:风廓线的大气风场显示这场大雪属于典型的安徽大雪天气形势。降雪前925hPa左右高度可见东风气流,当东风气流转为西北气流时,降雪天气开始;500~850hPa为西南暖湿气流;降雪时低层冷平流,中高层暖平流,逆温结构有助于降雪的发生;西北气流向上扩展到700hPa高度以上时,降雪趋于结束。雨转雪时,垂直风速由4~7m/s迅速减小到1.4~1.9m/s,表明了雨雪性质的转换,产生的原因是雪的下降速度小于水滴。当垂直风速出现了0值和弱负值,说明大气层结恢复静力平衡,降雪趋于结束。此外,折射率结构常数的变化也同样与降雪过程相对应。

Application of wind profiler radar in a heavy to torrential snow weather process

This paper uses the data collected by the boundary-layer wind profiler radar to analyze a heavy to torrential snow weather process occurred on December 29,2012 in Wuhu. According to the wind field acquired by the wind profiler, a conclusion can be drawn that this weather process is a classic severe snow synoptic situation of Anhui province. East flow can be seen on the 925hpa level before the snowfall, and when the east flow was converted to the west flow, the snowfall occurred. The southwest warm and humid air appearred between 500 and 850hpa level. During the snowfall process, cold advection was on low level while warm advection was on high level, and this temperature inversion structure promoted the snowfall. When the northwest flow expanded upward to 700hpa, the snowfall came to an end. When rain was converted to snow, the vertical wind speed decreased from 4- 7m/s to 1.4-1.9m/s. That indicates the conversion was caused because the fall speed of the snow was less than the rain drop. The occurrence of zero and slight negative values of the vertical wind speed indicated the restoration of static balance of the atmosphere structure and the ending of the snowfall. The variation of the structure and constant of refractive index was also consistent with the snowfall process.