陕西省近47a来降水变化分析

Analyses of Precipitation Change in Shaanxi Province during 1961-2007

利用陕西省78个气象观测台站1961—2007年逐日降水量资料,分析了陕西地区降水变化特征及其对旱涝的影响。结果表明,47a来陕西地区的年降水量呈明显的减少趋势,减少幅度为18.4mm/10a,主要表现为春秋季降水的减少;降水日数的变化呈减少趋势,递减率为3.2d/10a,主要体现在小雨和中雨事件频率的下降;但是平均降水强度总体呈微弱的增强趋势,主要原因是大雨和暴雨频次的增加。在显著变暖的20世纪90年代以后,雨日减少,但暴雨增多,强度增强,该区域降水有向不均衡、极端化发展的趋势,旱涝灾害也有加重趋势。

Based on the daily precipitation data from 78 stations in Shaanxi during 19612007,the spatial and temporal distributions of precipitation amount,frequency and are analyzed.The main conclusions are as follows：The annual precipitation decreased by a rate of 18.4 mm per 10 years,being manifested by precipitation decrease in spring and autumn;The annual rainy days had a significantly decreasing trend at a rate of 3.2 days per 10 years,which was mostly due to the decrease of light and middle rain events;The intensity of precipitation on the whole showed a slight increasing trend due to the increase of heavy rain and rainstorm frequencies.In a word,precipitation change in Shaanxi province has been becoming uneven and extreme since warm 1990s,and drought and flooding calamities will exaggerate.