洞庭湖流域近58年季节性干旱时空分布及大气环流分析

Based on the monthly precipitation data of 103 meteorological stations from 1960 to 2017 in the Dongting Lake Basin, the monthly mean reanalysis data from NCEP/NCAR and Z-Index, we analyzed spatial-temporal variation characteristics of seasonal drought in recent 58 years in the Dongting Lake Basin and displayed the features of synchronous atmospheric circulation with different range levels of drought, in order to enhance the understanding of seasonal drought. The results shows that, the Z-index in the Dongting Lake basin exhibits significant inter-annual and inter-decadal variation characteristics in the past 58 years. To be more specific, the Z-index is characterized by relatively severe drought in 1960s, obvious inter-annual transitions of drought and flood in 1970s and 1980s, wet phase in 1990s, and an inter-decadal transition of drought and flood after entering 21st century. The droughts in spring, summer and winter occurred mostly before 1990, and the seasonal drought in the basin exhibits different spatial distribution characteristics in different ages. The multi-annual average drought frequency of each station in the basin intermediates between 10% and 30% nearly. Through the features of synchronous atmospheric circulation, the Eurasian pattern teleconnection wave train exerts an important effect on the drought in every season in the basin. The East Asia/Pacific pattern and the Silk Road pattern teleconnection have noticeable effect on the intensity and position of the western pacific subtropical high in summer and autumn. The drought are mainly affected by the cold airflow from the north in spring and winter, and the drought with larger area is more likely to occur in the summer(autumn) when the subtropical high is weak(strong) and northerly.