新疆昌吉市主汛期降水的日变化特征

The Characteristics of Rainfall Diurnal Variation during Flood Season in Changji City,Xinjiang

基于昌吉市2009—2015年逐时自动降水资料,分析了主汛期（5—8月）降水的日变化特征。结果表明,降水主要集中在夜间21：00至翌日03：00,最大值出现在00：00,最小值出现在14：00;逐时降水频次为明显的单峰型,降水易发生在21：00至翌日08：00,降水频次的高峰值出现在01：00,降水最不易产生于午后14：00—18：00;降水强度变化的波动性较大,大值区出现在21：00至翌日02：00和15：00—19：00,最高值出现在18：00,最低值出现在03：00—08：00;在≥0.1 mm、≥1 mm和≥3 mm的逐时降水频次中,夜间降水频次较白天高,≥0.1 mm的降水出现次数较多;降水主要以夜雨,且以短时间（1~4 h）的降水为主,贡献率最大的是持续7 h的降水。

Based on the hourly automatic rainfall data in Changji station from 2009 to 2015, the characteristics of rainfall diurnal variation during main flood season （5-8 month） were analyzed. The results showed that the rainfall was mainly concentrated between 21：00 pm to 03：00 am（BT）, with the maximum value of rainfall appearing at 00：00 am （BT）, the minimum value appearing at 14：00 pm （BT）. Hourly precipitation frequency was obviously single peak type, the high value of rainfall frequency occurred at 21：00 pm to 08：00 am （BT）, the precipitation frequency peak appeared at 01：00 am, it was not easy to generate at 14：00 pm to 18：00 pm（BT）. The fluctuation of rainfall intensity was large, the large value area was appeared at 21：00 pm to 02：00 am and 15：00 pm to 19：00 pro, the maximum appeared at 18：00 pm （BT） and the minimum occurred at 03：00 am to 08：00 am （BT）. According to the different levels, defined by the hourly rainfall of ≥0.1 mm or ≥ 1 mm or ≥ 3 mm respectively, rainfall easily occurred at night than day, and the hourly rainfall ≥ 0.1 was more frequent than other levels. Precipitation mainly occurred in night, mostly 1-4 hours rainfall, the duration of 7h made the greatest contribution to the total rainfall.