近50年中国干湿气候界线波动及其成因初探
THE FLUCTUATION OF DRY AND WET CLIMATE BOUNDARY AND ITS CAUSAL ANALYSES IN CHINA
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摘要: 文中在10a际尺度上详细分析了中国干湿气候界线波动与气候的干湿变化,得出:过去50a中国干湿气候界线波动显著,区域差异大,呈现出整体移动和东西、南北相异波动的特征。20世纪60～70年代中国干湿气候存在一次突变,由较湿润变为干旱,但各地干旱程度不同。干湿气候界线波动与气候的干湿变化具有显著的年代际特征。在此基础上分析了气候界线波动的可能原因,中国干湿气候界线的波动与气候的干湿变化是西太平洋副热带高压强度位置导致的东南季风、孟加拉湾暖流所导致的西南季风以及高原季风、中纬度西风环流等综合作用的结果。中国各地区干湿位相变化不一致,区域差异大,是不同环流以及环流的不同强弱组合所致。东南季风、西南季风、高原季风、中纬度西风环流、西太平洋副热带高压的年代际变化是过去50a中国干湿气候界线波动与气候干湿变化年代际变化的根本原因。20世纪60～70年代的干湿突变,是整个北半球大气环流异常的结果。Abstract: Based on the yearly precipitation, annual mean wind, solar radiation data during 1951-1999 of 295 stations, the aridity index is calculated in this paper. According to aridity index(D), the climatic regions in China are delineated into three types, namely, arid region, semi-arid region and humid region. D=0.20 is the boundary between arid and semi-arid region. D=0.50 is the boundary between semi-arid and humid climate region. Dry and wet climate in China fluctuate markedly and differentiate greatly in each region over past 50 years. Semi-arid region is the transitional region between humid and arid regions, the border belt of monsoon in China and the susceptible region of environmental evolution.
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