科尔沁沙地奈曼地区降水变化特征分析

Characteristics of Precipitation in Naiman Region of Horqin Sandy Land

降水的分布特征和趋势分析对于研究区域水分动态和水资源合理评价具有重要的生态学意义。以奈曼旗气象局49a的降水数据分析了该区域降水的变化趋势与特征,结果表明:奈曼地区49a来平均降水量为351.7mm,春季降水呈现逐年增加的趋势,而夏季、秋季和冬季降水逐年减少,夏季降水最多,为年平均降水的68.6%;年降水中以7月的降水量最多,占年降水总量的30.4%;降水量介于300～350mm的年份最多,占28.6%,小于多年平均降水量的年份占63.3%。年降水300mm以上的概率为67.4%,而大于多年平均降水量的概率仅为38.8%;降水年际变率较大,变异系数为25.1%,总体趋势是降水逐年减少,有趋于更干旱化的特点。

There are important ecological significance of analyzing distribution characteristics and trends of precipitation for study of regional water dynamics and rational evaluation of water resource.In the present study,the variable trends and characteristics of regional precipitation were analyzed by using 49-year precipitation data collected from Naiman Weather Bureau.The results show that the mean annual precipitation is 351.7 mm（during 1961-2009） in Naiman region.Precipitation increases in spring year by year,and decreases with years in summer,autumn and winter.Precipitation reaches maximum level in summer,which accounts for 68.6% of mean annual precipitation.Precipitation in July reaches maximum in a year,which represents 30.4% of the total annual precipitation.The proportion of year of 300-350 mm precipitation is common,and it accounts for 28.6%,while the year of annual precipitation less than mean annual precipitation accounts for 63.3%.Probability of annual precipitation more than 300 mm is 67.4%,while annual precipitation more than 351.7 mm only accounts for 38.8%.The interannual variability of precipitation is large,and the coefficient of variation is 25.1%.This indicates that total trends of precipitation decrease year by year,which shows a trend of aridization in this area.