西江流域枯季降雨时空演变特征及典型干旱年环流分析  

Spatio-temporal variations of dry season rainfall and circulation analysis of typicaldrought years in the Xijiang River Basin

作　　者：杜勇[1] 张尹 余欣洋 DU Yong;ZHANG Yin;YU Xinyang(Bureau of Hydrology of Pearl River Water Resources Commission of Ministry of Water Resources,Guangzhou 510611;Zhongshan Meteorological Service,Zhongshan 528400)

机构地区：[1]水利部珠江水利委员会水文局,广州510611 [2]中山市气象局,中山528400

出　　处：《中国防汛抗旱》2024年第11期51-55,共5页China Flood & Drought Management

基　　金：国家自然科学基金重点项目(52439002)。

摘　　要：利用西江流域1961—2023年降雨数据和ERA5(欧洲中期天气预报中心第五代全球气候和天气再分析产品)资料,分析了西江流域枯季降雨的时空变化规律,并对历史上干旱典型年的枯季850 hPa风场距平和500 hPa位势高度场距平合成场进行了分析。结果表明,西江流域枯季降雨存在明显的年代际周期变化。旱情较重的年份有可能出现在枯季降雨正距平的次年,因此每年在进行西江流域枯季降雨预测时,也应关注前一年枯季降雨距平,警惕丰枯急转。西江流域较干旱的年份,枯季无降雨的时间总体可能偏长,但是连续无降雨的时间不一定偏长。空间上,西江流域枯季降雨整体呈现“西少东多”分布,且流域西北部降雨有减少趋势,流域东北部降雨有增加趋势。当欧洲槽偏强、极涡偏弱、巴尔喀什湖附近的高压脊偏强、东亚大槽偏强、华南区域上空低层为偏北距平风场、冷空气活跃且强度较强时,西江流域容易出现大范围干旱。The rainfall data from 1961 to 2023 in the Xijiang River Basin and ERA5(the fifth generation global climate and weather reanalysis product of the European Centre for Medium Range Weather Forecasts)data are used to analyze the spatiotemporal variations of dry season rainfall in the basin and the composite anomalies of 850 hPa wind and 500 hPa geopotential height during typical drought years are examined.The results show significant decadal variations in dry season rainfall in the Xijiang River Basin.Typical severe drought years may follow years which have positive anomalies of dry season rainfall,highlighting the need to consider rainfall of previous dry season when forecasting the next dry season rainfall in the basin with the attention of sudden turn of floods and droughts.In typical drought years,the duration without rainfall in the dry season in the Xijiang River Basin may generally be longer,but the duration without continuous rainfall days may not be longer.Dry season rainfall in the Xijiang River Basin shows an overall"less in the west,more in the east"distribution,with decreasing rainfall trends in the northwest and increasing trends in the northeast of the basin.Factors such as a strong European trough,weak polar vortex,strong high-pressure ridge near Lake Balkhash,strong East Asian trough,anomalous north wind over South China,and active and intense cold air may make the Xijiang River Basin to be widespread droughts.

关 键 词：西江流域 枯季 降雨 环流分析 

分 类 号：P426.6[天文地球—大气科学及气象学]