洞庭湖流域夏季降水特征及旱涝年份大气环流分析

Characteristics of summer precipitation in Dongting Lake basin and analysis of atmospheric circulation in drought and flood years

基于洞庭湖流域96个气象站点1961-2015年逐月降水数据和NCEP/NCAR再分析资料,对洞庭湖流域55年夏季降水的时空变化与典型夏涝年、夏旱年的大气环流特征进行分析。结果表明:55a间流域夏季降水存在明显的年际和年代际变化特征,存在准3a和20a周期。流域夏季平均降水量呈现由中北部平原地区向四周山区递增的空间分布特征。从大气环流和水汽输送及辐合形势来看,典型夏涝(旱)年,对应着西北太平洋副热带高压面积偏大、强度偏强和流域上空水汽的异常辐合(辐散)。

Based on the monthly precipitation data and NCEP/NCAR reanalysis data of 96 meteorological stations in the Dongting Lake basin for 1961-2015 years, this paper analyzed the temporal and spatial variations of the summer precipitation in the Dongting Lake in 55 years and the characteristics of the atmospheric circulation in the typical summer flood years and summer drought years. The results showed that there are distinct interannual and interdecadal variabilities in summer precipitation in 55 yr and there are quasi 3 yr and 20 yr cycles. The average summer precipitation in the basin had a spatial distribution characteristic of increase from the middle north plain to the surrounding mountainous area. From the situation of atmospheric circulation, water vapor transport, and convergence, the typical summer flood（drought） year corresponds to the large area of the subtropical high in the Northwest Pacific, the strong intensity, and the anomalous convergence of the water vapor above the river basin.