新疆短时强降水天气主要流型及环境参量特征分析

Characteristic Analysis of Main Weather Pattern and Environmental Parameter of Short-Time Heavy Precipitation in Xinjiang

利用近10年新疆暖季(5—9月)常规观测、区域自动站小时降水资料,对468个短时强降水过程的主要流型、关键环境参数特征及预报阈值进行讨论。结果表明:新疆短时强降水的流型有中亚低槽(涡)、西西伯利亚低槽(涡)、西北气流等3种,中亚低槽(涡)是影响新疆短时强降水的主要流型;探空温湿廓线可分为Ⅰ型(整层干)、Ⅱ型(上干下湿)、Ⅲ型(上湿下干)和Ⅳ型(整层湿),Ⅰ型和Ⅲ型是新疆短时强降水的主要类型;中亚低槽(涡)主要是探空温湿廓线Ⅲ、Ⅳ型,西伯利亚低槽(涡)多为Ⅰ、Ⅱ型,西北气流Ⅰ、Ⅲ型居多。3种流型对应的主要环境参量最低阈值:850 hPa与500 hPa温差分别为24.0℃、25.0℃和27.0℃、地面至700 hPa露点温度均值分别为3.0℃、2.0℃和2.9℃;CAPE分别为117 J·kg^(-1)、146 J·kg^(-1)和103 J·kg^(-1)、0~6 km垂直风切变分别为0.8×10^(-3)s^(-1)、1.0×10^(-3)s^(-1)和0.5×10^(-3)s^(-1)。本文对新疆短时强降水主要流型配置、短临预报潜势及阈值进行初探,为新疆短时强降水短临预报预警提供支撑。

Using the conventional observation data and automatic regional station hourly precipitation data of Xinjiang in the warm season(May to September)for the past ten years,468 short-time heavy precipitation processes are counted,and their main weather flow,key environmental parameter characteristics and forecast thresholds are discussed.The conclusions are as follows.The effect systems primarily were the central Asia trough(vortex),West Siberia trough(vortex)and Northwest flow.Among the three,the central Asia trough(vortex)occurred most freguently.The temperature and relative humidity profiles from radiosonde sounding can be classified into four types:typeⅠ(air with the whole atmosphere dry),typeⅡ(air with upper-layer dry and lower-layer wet),typeⅢ(air with upper-layer wet and lower-layer dry),and typeⅣ(air with the whole atmosphere wet).The short-time heavy precipitation occurred most freguently under the atmosphere of typeⅠand typeⅢ.The central Asia trough(vortex)processes were mainly typeⅢor typeⅣ.Most cases of the West Siberia trough(vortex)belonged to typeⅠand typeⅡ.TypeⅠand typeⅢwere in the majority of that under the Northwest flow.The corresponding minimum thresholds of the main environmental parameters for the three flow patterns were:24.0℃,25.0℃,27.0℃for the temperature difference between 850 hPa and 500 hPa;3.0℃,2.0℃,2.9℃for the average dew temperature from the ground to 700 hPa;117 J·kg^(-1),146 J·kg^(-1),103 J·kg^(-1)for CAPE;0.8×10^(-3)s^(-1),1.0×10^(-3)s^(-1),0.5×10^(-3)s^(-1)for 0-6 km vertical wind shear.In order to provide technical support to the short-time heavy precipitation nowcasting and warning,the preliminary exploration on main weather flow configuration,potential short-impending prediction and thresholds are made.