近45年内蒙古大兴安岭林区不同等级降水变化特征

Dynamic characteristics of different grade precipitation events during past 45 years in Daxing'anling forest region,Inner Mongolia

利用内蒙古大兴安岭林区11个气象站点1971—2015年逐日降水资料,采用一元线性趋势、反距离加权(IDW)插值法和Morlet小波分析方法,分析了该林区近45年不同等级降水(小雨、中雨和大雨)日数及强度的时空变化特征。结果表明:(1)小雨日数呈现减少趋势,中雨、大雨日数变化趋势不明显;不同等级降水强度年际变化趋势不明显,进入2000年以后,大雨强度波动趋于平缓;(2)各级降水对总降水的平均贡献率大小依次为小雨>中雨>大雨;(3)不同等级降水强度均存在不同时间尺度的周期变化规律,小雨存在7、13、19、27 a左右的周期变化,中雨存在22、10 a左右的周期变化,大雨存在25、7 a左右的周期变化;(4)在空间分布上,中雨、大雨日数和各级降水强度均呈现由西向东逐渐增加的空间分布趋势,小雨日数却呈相反趋势;(5)林区各地的降水量年际变化差异不显著。研究结果可为该地区林业、农业生产提供基础性参考。

Based on the daily precipitation observation data of 11 meteorological stations from1971 to 2015 in Inner Mongolia Daxing＇anling forest region,the linear regression,inverse distance weighted（IDW） interpolation and Morlet wavelet analysis method were employed to analyze the spatiotemporal dynamics of precipitation days and intensity at different grades in Daxing＇anling forest region,Inner Mongolia.The results showed that：（1） Light-rain days showed a decreasing trend,while the variation trends of moderate-and heavy-rain days were not obvious.The variation trend in annual precipitation intensity at each grade was not significant.The fluctuation of heavy-rain intensity tended to be gentle after 2000.（2） The average contribution rate of precipitation at different grades was in the order of heavy rain〉moderate-rain〉light rain.（3） Different grades of precipitation intensity showed different periodic variation patterns on different time scales.The light-rain showed periodic variations on 7,13,19,27 a,moderate-rain on 22 and 10 a,and heavy rain on 25 and 7 a.（4） Spatially,moderate-rain days,heavy-rain days and precipitation intensity at all levels showed a gradual increase trend from the west to the east,while light-rain days showed an opposite pattern.（5） There was no significant difference in spatial variation of annual precipitation in Daxing＇anling forest region.The results can provide basic reference for forestry and agricultural production in this region.