辽西北地区45年来降水量变化趋势及其空间差异

辽西北地区是辽宁省的重点旱区。选取该地区39个雨量站1966~2010年的逐月降水资料,在分析该地区年、季降水量基本空间分布特征的基础上,采用线性倾向法分析其全年及各季降水量的长期变化趋势,并分析该趋势在空间上的差异性。结果表明,辽西北地区降水量季节分配不均,夏季占全年降水量的2/3;春、秋季多雨中心位于黑山县、新民市,冬季北移,夏季位于南部的绥中县和兴城市;全区春、冬季平均降水量呈增加趋势,夏、秋季呈减小趋势;年际变化上,春季降水距平高频振荡明显,夏季与年降水距平变化相似,秋季有尺度较长的丰枯周期,冬季降水量负距平年份较多,常连续出现;年降水量线性倾向与年降水量空间分布呈显著负相关,由东南向西北递增;季降水量空间分布为东南—西北分异,而其线性倾向值则以东—西分异为主。

Variation Trend and Its Spatial Distribution of Precipitation in Northwestern Liaoning Province during Recent 45 Years

Northwestern Liaoning Province is a key drought area. Based on monthly precipitation data of 39 rainfall stations from 1966 to 2010 in this area, the linear trends and their spatial variability of annual and seasonal precipitation were investigated. Seasonal distribution of precipitation in this area is not uniform, with two thirds of the annual precipitation occurs in summer. Precipitation center is in Heishan county and Xinmin city in spring and autumn and moves northward slightly in winter, but in summer, by contrast, it moves to Suizhong county and Xingcheng city, southern part of the study area. Regional average precipitation shows upward trend for spring and winter and downward trend for summer and autumn. Inter-annual variations are different for different seasons. Spring precipitation is characterized by interannual oscillation, it is similar to annual precipitation for summer, the period becomes longer and significant for autumn, years of negative precipitation anomaly are more and occurred consecutively for winter. Spatially, annual precipitation trends are negatively correlated with annual precipitation, increasing from southeast to northwest. The seasonal precipitation decreases from southeast to northwest, while the linear trends of seasonal precipitation shows gradients from east to west.