1971~2017年新疆夏季分级降水特征

利用1971~2017年新疆100个气象观测站的逐日降雨资料，在降水分级的基础上，采用EOF分解、Mann-Kendall检验、小波分析等方法对新疆夏季降水特征进行研究，结果表明:受天山山脉影响，新疆夏季降水主要集中在天山山脉附近，呈由北向南递减的空间分布特征；近47年新疆区域平均的夏季降水呈持续增长趋势，存在明显的多时间尺度波动，并在1987年发生由少到多的突变；EOF分析的前四个模态依次反映出新疆夏季降水具有整体一致、南-北向相反、东-西向相反以及中部与周边地区相反的变化特征；从空间分布看，新疆夏季各级降水的雨量与雨日均呈现明显上升趋势，其气候变化趋势系数与夏季降水基本一致，表现出北疆大于南疆、西部大于东部、山区多于盆地和谷地的空间分布特征；从时间变化看，新疆区域平均的夏季各级降水的雨量与雨日以上升趋势为主，其中暴雨的上升趋势最为显著，大雨次之，小雨和中雨最弱；新疆区域平均的夏季各级降水均表现出多尺度周期振荡特征。 

Characteristics of Grading Precipitation in Summer in Xinjiang from 1971 to 2017

Using the daily rainfall data collected from 100 meteorological observation stations from 1971 to 2017, based on the precipitation classification, the characteristics of summer precipitation in Xinjiang were studied by EOF decomposition, Mann-Kendall test and wavelet analysis. The results show that: summer precipitation is mainly concentrated near the Tianshan Mountains and decreased from north to south; the average summer rainfall in the past 47 years has shown a continuous increasing trend with obvious multi-decade-scale fluctuations, and occurred abrupt changes from less to more. The first four modes of EOF analysis successively reflect the change characteristics of summer precipitation in Xinjiang, which are generally consistent, opposite in south-north direction, opposite in east-west direction and opposite in central and surrounding areas. From the spatial distribution, the rainfall and rainy days of summer precipitation at all levels in Xinjiang show an obvious upward trend, and the climate change trend coefficient is basically consistent with summer precipitation, showing the spatial distribution characteristics of northern Xinjiang greater than southern Xinjiang, western Xinjiang greater than eastern Xinjiang, and mountainous areas more than basins and valleys. From the point of view of time change, the average rainfall and rainy days at all levels in summer in Xinjiang are mainly on the rise, and the upward trend of rainstorm is the most significant, followed by heavy rain, light rain and moderate rain. The average summer precipitation in Xinjiang shows multi-scale periodic oscillation characteristics.