摘要
对 2 5a(1 971～ 1 995年 )逐候东半球热带外 50 0 h Pa高度距平场进行小波分析和旋转主成分分析 ,研究了 30～ 60 d低频振荡的时空变化及其与长江下游夏季旱涝和暴雨频数年际变化的关系。结果表明 :6～ 1 0月欧亚型 (EU)低频振荡强度与长江下游暴雨频数成显著负相关 ,同时 ,提出了能揭示变量间非线性关系的对比函数分析 (CFA)方法 ,发现当 5～ 8月西太平洋型 (WP)低频流型偏强时 ,长江下游暴雨频数增加 ,容易发生洪涝 ;反之 ,无明显影响。仅当前期 3～ 5月南亚大陆型偏强时长江下游降水量偏少 ,而 3～ 5月南亚大陆型偏弱时暴雨频数明显增加。因此 ,长江下游旱涝与低频流型异常之间同时存在线性和非线性相关。
The relationships between the interannual variations on the intensity of LFO(30-60 days) of Eurasian circulation during summer half years and the rainfall in summer and the number of heavy rains in the low reaches of Yangtze River have been investigated by using wavelet analysis and rotated principal component analysis based on the data of the pentad mean 500 hPa height field over the Eastern Hemisphere for the 25 years period 1971-1995. The results indicated that there exists a dominant negative correlation between the intensity of LFO(30-60 d) for Eurasian pattern (EU) from June to October and the number of heavy rains in the low reacher of Yangtze River. Meantime , the contrast function analysis (CFA) is proposed with identifying nonlinear relationships between the two variables. In addition,it is found that the number of heavy rains is enhanced and the floods are caused easily when the intensity of the Western Pacific pattern (WP) enhances during the period of May-August by means of the CFA, but the effect is less significant when WP pattern reduces.The rainfall in summer is reduced signifiantly,only when the intensity of the Southen Asia pattern (SA) is enhanced but the number of heavy rains increased, only when the lintensity of SA is reduced during the period of March-May. Hence, the linear or nonlinear correlation may exist simultaneously between the drought/flood and low frequency flow patterns.
出处
《气象学报》
CSCD
北大核心
2001年第3期318-326,共9页
Acta Meteorologica Sinica
关键词
长江下游
旱涝
低频振荡强度
年际变化
对比函数分析
小波分析
Drought/flood in the low reaches of Yangtze River, LFO intensity, Interannual variation, Contrast function analysis (CFA), Nonlinearity.
