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江西省小时降水特征分析

Characteristics of hourly precipitation in Jiangxi

  • 摘要: 利用1977年8月—2017年7月江西省83个国家自动气象站的逐时降水资料,分析了江西省小时降水的时空分布特征。结果表明:(1)年均降水小时数大值中心呈沿东、西部山脉的带状分布,江西北部鄱阳湖平原地区小时数相对较少,小时降水强度江西北部和东南部大;(2)小时降水事件平均历时由南向北逐渐增大;短历时(1~6 h)对总降水量的贡献率最高,贡献率空间分布由南向东北方向递减;历时超过6 h的降水事件,随着历时的增长大值中心向江西东北方向移动;(3)江西省小时强降水事件频次分布东高西低,且随着强降水等级的提升,高值中心逐渐北移;(4)小时降水主要出现在下午15—18时,多以短历时降水事件呈现,而中历时(8 h左右)的降水易出现在早晨07—08时;(5)近40 a赣北东部小时降水事件频次和累计降水量增加趋势显著。

     

    Abstract: Based on the hourly rain-gauge data from 83 National Weather Stations in Jiangxi area from the period of August 1977 to July 2017, the basic precipitation distribution and diurnal variation characteristics were analyzed. The results are listed below:Firstly, high-value center of annual precipitation hours has a zonal distribution along eastern and western range. There is less annual precipitation hours at plain of Poyang, north area in Jiangxi. Characteristics of hourly precipitation intensities at north and southeast of Jiangxi are:extreme hourly precipitation hours in March and extreme cumulative hourly precipitation in June. The diurnal variation curve of annual hourly precipitation hours has two peaks appearing at 6:00-8:00 and 18:00-20:00. Secondly, the short duration precipitation within 6 hours accounts approximately for 3/4 of the total precipitation. The average hourly duration precipitation last shorter and shorter from south to north, but it has the highest contributing rate for the total precipitation and its spatial distribution rate is decreasing progressively from south to northeast. For those duration precipitation over 6 hours, their contributing rate centers mainly locate at north area and are moving northeastwards with the growth of duration precipitation. Thirdly, hourly precipitation frequency is higher in east than west. Its high-value center moves northward with the ascension of precipitation level. Fourthly, the hourly accumulative precipitation appears mainly at 15:00-18:00 and is presented with short duration precipitation, and the middle duration precipitation (8 hours or so) occur easily in the morning around 7:00-8:00. Finally, the hourly precipitation frequency and accumulative precipitation of eastern part in south have a prominent increasing trend in the past 40 years, and the trend passed 5% significance level test.

     

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