汉江流域降水结构时空特征及影响因素分析

Analyses of Rainfall Characteristics and Influencing Factors in Hanjiang River Basin

利用汉江流域32个气象站1961～2016年逐日降水资料,分析了汉江流域降水时空分布特征,并探讨了海温及大气环流对流域降水的影响。结果表明:雨量和雨日空间分布相似,小雨、中雨的雨量和雨日由西南向东北递减,降水中心位于西南和东南部;流域东北部大雨以上量级降水由偏少转为偏多,而雨强空间分布则没有明显规律。流域降水集中度自东南向西北逐渐增加,降水集中期逐渐推迟。海温对降水的影响存在季节差异,春季、夏季和秋季降水分别受前期南印度洋、热带北大西洋和热带中东太平洋海温影响,冬季降水则受海温影响不明显;大尺度大气环流对降水存在影响,冬季欧亚遥相关型和春季西太平洋遥相关型均引起冬季风强度变化来影响冬季和春季降水,夏季副高位置和乌山阻高以及秋季巴湖低槽和印缅槽强度则均通过冷空气和暖湿气流强度及交汇位置来影响夏季和秋季降水。

Based on the daily precipitation data during 1961-2016 of 32 stations in Hanjiang river basin,the spatial and temporal distribution characteristics of precipitation are analyzed,and the impact of sea surface temperature and atmospheric circulation on the precipitation in Hanjiang river basin are discussed. The results show that: The spatial distribution of rainfall is similar to that of rainy days of each grade,and the rainfall and rainy days of light rain and moderate rain gradually reduce from the southwest to the northeast;The precipitation centers are located in the southwest and the southeast,and there are more rainfall of heavy rain and above in the northeast;But the rainfall intensities of each grade have no obvious regularity;The PCD increases and the PCD postpones gradually from the southeast to the northwest;There are differences between driving factors of seasonal precipitation;In the aspect of the impact of sea surface temperature on seasonal precipitation,spring precipitation has a negative correlation with the Southwest Indian Ocean sea surface temperature from last November to February,summer precipitation has a positive correlation with the tropical North Atlantic Ocean sea surface temperature from February to August,and autumn precipitation has a negative correlation with the tropical Central-eastern Pacific Ocean sea surface temperature from April to September,but winter precipitation is little affected by sea surface temperature;And in the aspect of the impact of large-scale atmospheric circulation on seasonal precipitation, spring precipitation is related to western Pacific teleconnection pattern, summer precipitation is affected by the position of western Pacific subtropical high and the Ural blocking high,autumn precipitation is related to the India-Burma trough and the low trough of Balkhash Lake,and winter precipitation is influenced by the Eurasian teleconnection pattern;Therefore,atmospheric circulation changes the East Asian winter monsoon intensity to impact on the precipitation in spring and winter and meeting location and intensity of cold air and warm and wet air to influence precipitation in summer and autumn.