陕西黄土高原15时段降水特征分析

采用陕西黄土高原区38个气象站近几十年的时段降雨量数据，分析了15个时段降水量的分布、变化特征。得到时段降雨量的变化周期、趋势等。对当地农业、水土保持等工作有参考作用。结果表明:陕西黄土高原15个时段最大降水量变幅明显，同时段降水最大值与最小值之间相差11.6～18.5倍之多。最大降水强度为0.2～4.4 mm，曲线呈指数分布，时间越短，降水强度越大。15个时段最大降水量以盛夏的7—8月居多，一日内12:00—20:00出现次数在70%以上。两个或以上县的各时段降水极值很少出现在同一次降水过程中，说明陕西黄土高原高强度降水范围较小，以影响1个县为主。各站降水累积距平变化趋势不相同，但近几年普遍有增强趋势。存在突变的县比较少，淳化在2004年出现突变。降水序列具有3 a，6～8 a，16 a的周期变化现象。

Analysis of Precipitation Characteristics of the Fifteen Periods on the Loess Plateau of Shaanxi Province

In this paper, the precipitation distribution and the precipitation intensity of 15 periods precipitation was analyzed based on 38 weather stations in recent decade periods of precipitation data in the Loess Plateau of Shaanxi Province. The cycle time of periods precipitation and the trend were obtained. It is used for reference to the local agriculture and soil and water conservation practices. According to the precipitation of 15 precipitation periods in the calendar year in 38 stations on the Loess Plateau of Shaanxi Province, a preliminary analysis about precipitation intensity of climate profile was carried out. The results show that the maximum precipitation of 15 periods of the Loess Plateau of Shaanxi Province had an obviouse change and the same paragraph precipitation between the maximum was the 11.6 to 18.5 times. The curve of maximum precipitation intensity is discribed by expotential function and maximum precipitation intensity is 0.2 mm and 4.4 mm, the shorter the time and the greater the precipitation intensity. 15 precipitation periods of maximum precipitation appear in midsummer mostly from July to August, and the number of occurrences is more than 70% within a day 12 hours to 20 hours. Two or more counties each period precipitation extremes rarely appear with a precipitation process, so the small range of the high-intensity rainfall presents in the Loess Plateau of Shaanxi Province, and mainly impacts a county. The precipitation cumulative anomaly trend in each station is not the same, but increased greatly in recent years generally. The county mutation is less, the change of Chunhua county apeares suddenly in 2004. The precipitation sequence has phenomenon of cycle change for as 3 a, 6～8 a and 16 a.