1972~2017年河北省夏季降水的时空变化特征

Temporal and Spatial Variation Characteristics of Summer Precipitation in Hebei Province During 1972-2017

利用河北省1972~2017年(不含2014年)135个地面观测站的逐日降水资料,对河北省夏季(6~8月)降水过程的时空变化特征进行诊断分析。结果表明,近45年河北省夏季年均降水量、降水强度和降水极值均呈现出从东南沿海向西北内陆逐渐递减的分布形势,降水频率的分布则与其相反。降水的年均降水量在河北省北部呈下降趋势,南部呈上升趋势,年均降水量的减少主要是降水频率的减少造成的。暴雨的空间分布与地形分布关系密切,年均降水量与降水强度增强的区域均位于张家口、承德北部、太行山西侧的高原区和秦皇岛东部的沿海地区,其他地区二者均呈下降趋势。各类2、3、4、5 d及其以上降水过程的频数均具有年际和年代际变化特征,且以下降趋势为主,持续2、3 d降水过程频数的空间分布较为均匀,而持续4 d及其以上降水过程频数的年际变化明显。

In this study,the daily precipitation data of 135 meteorological stations during the period 1972-2017(excluding 2014)in Hebei Province were used to analyze the temporal and spatial variation characteristics of summer(June-August)precipitation.The results show that the average annual summer precipitation,precipitation intensity and precipitation extremes near the past 45 years show a gradual decrease from the southeast coast to the northwest inland,while the distribution of precipitation frequency is the opposite.The average annual precipitation shows a downward trend in northern Hebei and an upward trend in the south.The decrease of average annual precipitation is mainly caused by the decrease of precipitation frequency.The spatial distribution of rainstorm is closely related to the topographical distribution.As a result,the areas where the average annual precipitation and precipitation intensity increase are in the plateau area of Zhangjiakou and northern Chengde,the plateau area on the west side of Taihang Mountain,and the coastal area on the east of Qinhuangdao.In the other areas,both parameters mentioned above show a downward trend.The frequencies of various persistent precipitation processes of 2,3,4,5 days and above all have significant inter-annual and inter-decadal variations and are dominated by a downward trend.The spatial distribution of the frequency of precipitation processes lasting for 2 and 3 days is relatively uniform,while the inter-annual variation of frequency of precipitation processes lasting for 4 days and above is obvious.