青岛冬半年降水相态统计分析及判别方法研究

Statistical analysis and discrimination criterion on precipitation types of winter half year in Qingdao

通过对2006—2015年青岛冬半年不同相态降水的统计分析得出,青岛冬半年纯雨日数1月最少,纯雪日数2月最多,12月和1月是雨夹雪及雨雪转换日数占当月降水日数比例最高的两个月。通过个例分析表明,雨雪转换过程多与冷空气入侵相联系。温度场和风场条件能较好地反映出雨雪转换的特征,降温和风向转换在850 h Pa以下层更为明显。探空资料分析表明,850 h Pa、925 h Pa、1 000 h Pa和地面气温对不同相态降水都有很好的指示意义,越低层指示性越好。0℃层高度对不同相态降水同样具有指示意义,100~500 m高度是雨雪转换的关键高度层;以不同高度层气温为指标确定出青岛冬半年降水相态预报判别指标。

Using the precipitation data collected in Qingdao from 2006 to 2015,different precipitation types during the winter half-year was analyzed. Result shows that the monthly rainfall-day is minimum in January and the snowfall-day is maximum in February. The sleet and rain-snow conversion events take the highest proportion of precipitation days in December and January. Cases study shows that the rain-snow conversion is closely related to cold air intrusion. The temperature and wind field can manifest the characteristics of the rain-snow conversion,especially in the level under 850 h Pa where the cooling and wind direction changing are more obvious. Soundings data show that temperature at the 850 h Pa,925 h Pa,1 000 h Pa and the ground temperature are good indicators for different precipitation types with the better correlation in the lower level. The level of 0 ℃ temperature is also an indicator for precipitation types,of which the altitude between 100 m and 500 m is the key level for rain-snow conversion. The discrimination of precipitation types in Qingdao mainly depends on the temperature at these key levels.