1961-2013年东北地区夏季降水变化趋势分析

选取东北地区84个气象站1961—2013年逐日降水资料，利用Mann-Kendall统计检验方法、线性回归、气候倾向率和变异系数方法分析了近50年东北地区夏季降水日数、降水量和降水强度的时空变化特征，讨论了夏季不同等级降水日数和降水强度变化趋势和变异场特征。结果表明:近53年，东北地区夏季降水日数呈显著的下降趋势，其变化总体呈现出60年代 > 70年代≈80年代 > 90年代 > 21世纪前13年（2001—2013年）的特征，而降水量和降水强度的升降变化并不显著。东北地区夏季小雨雨日总体呈下降趋势，其中，东北地区东南部降幅最大，平均为-2.5～-1 d/10 a；中雨雨日倾向率也以下降为主；大雨、暴雨雨日倾向率的下降区域位于黑龙江中部、吉林西北部和辽东半岛，而在辽宁中部、黑龙江西部和内蒙东北部为大雨和暴雨雨日上升区。东北地区夏季小雨雨强倾向率在东北地区东南部以上升为主，升幅为0～0.1 mm/10 a，而西北部主要以下降为主，降幅为-0.1～0 mm/10 a；东北地区夏季大雨和暴雨日数波动较大，尤以暴雨日数的波动最为显著，相比于大雨和暴雨，小雨、中雨雨日和雨强的变化都要更稳定。

Analysis on the Trend of Variation of Summer Precipitation in Northeast China During the Period from 1961 to 2013

Based on daily precipitation data obtained from 84 meteorological stations in northeast China during the period from 1961 to 2013, we analyzed the summer precipitation characteristics, the features of precipitation days and intensity characteristics of different grades of summer precipitation events. The results indicated that both summer precipitation days and light rain days presented the significant decreasing trend, while light rain days decreased by -2.5～-1 days/decade during the period from 1961 to 2013. The moderate rain day tendency rate also showed the decline trend, especially in eastern and southern parts of northeast China. The heavy rain and rainstorm day tendency rates declined in the middle of Heilongjiang Province, northwest Jilin Province and Liaodong Peninsula, and it presented the rising trend in the other areas. In recent 53 years, the light rain intensity presented the slight increasing trend with 0～0.1 mm/decade in eastern and southern parts of northeast China. However, the intensity of moderate and heavy rain showed the decline trend in most areas. The variation coefficients of heavy rain and rainstorm days were greater than light rain and moderate rain days. It could be seen that heavy rain and rainstorm days became unstable. These changes will lead to the increasing risk of flood disaster in this region.