1920年中国北方7省（市）大旱的灾情及其成因

分析了1920年中国北方7省（市）大旱的旱情及其形成的物理因素。结果表明：1920年中国北方的大旱灾以京津冀最为严重，范围大，且多灾并发，危害异常严重。从1918年夏季到1920年春季南方涛动指数为负位相，是此次大旱重要的热带环流年际变化背景；该年是近百年来西太平洋副热带高压最弱最偏东的一年，这是形成大旱的主要原因；强厄尔尼诺事件是大旱的重要原因；登陆台风偏少和台风位置偏东、偏南，是造成干旱的原因之一。

The Disaster and Causes of Serious Drought in Seven Provinces of Northern China in 1920

In order to understand the cause of especially big arid event during the period of the Republic of China, and to serve for the drought resistant disaster reduction, the situation and the causes of the severe drought happened in seven provinces of northern China in 1920 were analyzed. The results indicated that the drought occurred mainly in Beijing, Tianjin and Hebei. Meanwhile, the drought was associated with other disasters, producing a serious damage to local development. Negative phase of South Oscillation was the most out- standing circulation background of this extreme arid event from summer 1918 to spring 1920. It also shows that the west Pacific Ocean subtropical anticyclone in 1920 was the weakest and the most eastward in recent 100 years, which was the main reason causing the great drought. Moreover, the strong E1 Nino event, the lack of the landing typhoon, and the typhoon position being easterly and southerly were also the important reasons deducing the great drought. The above conclusions have universal significance.