1967—2017年新疆降水分配时空特征研究

Study on Temporal and Spatial Characteristics of Precipitation Distribution in Xinjiang from 1967 to 2017

利用新疆全域50个站台1967—2017年逐日降水资料,通过对降水集中度与集中期的计算,分析新疆降水年内分配的不均匀性。结果表明,研究时段内北疆多年平均降水日数大于50 d,西部、北部山区可达90 d,南疆仅西部、北部沿天山地区达30~50 d,南疆其余区域及东疆均小于20 d;新疆降水量呈现增加趋势,降水日数及降水强度均有所增加;降水变异系数与多年平均降水量呈负相关,即降水越多的区域,年际差异越小,全疆降水变异系数在0.20~0.65,呈由北向南递增态势;全疆降水集中度在0.17~0.78,自北向南增大,降水分配趋于集中,且研究时段内降水集中度以0.011/10 a速度降低;全疆降水集中期在6月中旬至8月初,自西南向东北推迟,南疆最先进入集中降水期;在典型年中,南北疆的变化以降水强度为主,东疆以降水日数变化为主;新疆降水存在显著周期,现在阶段处于25~32年的降水偏少周期,且处于降水集中度由低向高转变的交替过程中。

Based on the daily precipitation data of 50 stations in Xinjiang from 1967 to 2017,the heterogeneity of precipitation distribution in Xinjiang was analyzed by calculating the precipitation-concentration degree(PCD)and precipitation-concentration period(PCP).The results showed that the multi-year average number of precipitation days during the study period was greater than 50 days in northern Xinjiang and up to 90 days in the western and northern mountainous areas of northern Xinjiang.Only the western and northern areas along the Tianshan Mountains in southern Xinjiang reach 30-50 days,while the rest of southern Xinjiang and eastern Xinjiang were less than 20 days.Precipitation in Xinjiang showed an increasing trend,with an increase in the number of precipitation days and average precipitation intensity.The variation coefficient of precipitation was negatively correlated with the multi-year average precipitation,which meant that regions with more precipitation had less inter-annual variation.The variation coefficient of precipitation in Xinjiang was 0.20-0.65,with an increasing trend from north to south.The precipitation-concentration degree in Xinjiang was 0.17-0.78,increasing from north to south,and the precipitation distribution tended to be centralized.During the study period,the precipitation-concentration degree decreased at a rate of 0.011/10 a.The precipitation-concentration period in Xinjiang was from mid-June to early August,delayed from southwest to northeast,with southern Xinjiang being the first to enter the period of concentrated precipitation.In a typical year,the changes in southern and northern Xinjiang were dominated by changes in precipitation intensity and in eastern Xinjiang by changes in precipitation days.There were significant cycles of precipitation in Xinjiang,and the present stage was in a 25-32 a cycle of low precipitation and in the process of alternating from low to high precipitation concentrations.