新疆暖季短时强降水特征

基于新疆105个地面气象观测站2005—2015年5—9月逐时降水观测资料,分析短时强降水的时空分布特征和降水贡献率。结果表明:新疆暖季短时强降水频次分布,具有北疆多于南疆,山脉坡面多于谷地和沙漠的特点,但短时强降水的降水贡献率南疆反而高于北疆。短时强降水高频区位置由春到秋的季节性南北推移与太阳辐射和副热带锋区的南北推移密切相关;北疆和南疆短时强降水频次的月、旬分布均呈单峰形,但两者变化形态却有所不同,前者迅速增强、迅速减弱,后者迅速增强、缓慢减弱。全疆平均短时强降水频次的日内变化有3个峰值,主峰在午后(18:00—19:00),次峰在前半夜(22:00)和清晨(08:00),北疆与之相同,南疆3个峰值时间和强度均与之存在显著差异。

Characteristics of Short-duration Heavy Rainfall in Warm Season in Xinjiang

Based on the hourly precipitation data from the 105 meteorological stations in Xinjiang from May to September during the period of 2005-2015, the spatiotemporal characteristics of precipitation and the contribution rates of short-duration heavy rainfall (hereinafter referred to as SDHR) in Xinjiang were investigated. The results indicated that the frequency of SDHR in north Xinjiang was higher than that in south Xinjiang and higher on mountain slope than that in valleys and deserts. However, the contribution rate of SDHR in south Xinjiang was higher than that in north Xinjiang. The seasonal north-south shift of high frequency zone of SDHR was closely related to the north-south passage of solar radiation and subtropical zone from spring to autumn. The curves of monthly and ten-day average frequencies of SDHR in north Xinjiang and south Xinjiang were unimodal, but their variation was different. The monthly frequency of SDHR was increased at first and then decreased rapidly, while the ten-day one was increase rapidly but decreased slowly. There were 3 peak values of the daily variation of SDHR average frequency, the highest value occurred at 18:00-19:00 BT, the second and third ones at 22:00 BT and 08:00 BT respectively Compared with the whole Xinjiang and north Xinjiang, the occurring time and intensity of the three peak values were significantly different from those in south Xinjiang.