1991年汛期旱涝类型的气候振动

CLIMATE OSCILLATION OF THE SUMMER RAINFALL ANOMALY PATTERN FOR THE FLOOD SEASON OF 1991

1991年汛期我国旱涝的分布(江淮多雨、华北及江南少雨)与近五百年旱涝等级图 EOF展开的第三特征向量一致。通过对旱涝第三特征向量时间系数(1991年旱涝型指数)的分析,发现1991年旱涝型指数具有37年左右的布吕克纳周期,且与南方涛动指数的36.7年周期有关。还发现1991年旱涝型指数与全球温度的相关系数为0.41(P>0.001),与北太平洋海面温度场的相关分布则相似于厄尔尼诺时期海面温度距平场的分布,即在赤道东太平洋为正相关,在西风漂流区为负相关。因此1991年的旱涝分布,可能与旱涝型自身长期变化所处的阶段、全球气候的增暖、特别是与1991年处于 ENSO 事件的增强位相等气候背景有关。

The distribution of summer rainfall anomalies in 1991 consists with the EOF ex-panded third eigenvector from the《Yearly charts of dryness/wetness in China for thelast 500-year period》.By analysing the time coefficient of the third eigenvector it isfound that the dryness/wetness pattern index in 1991 appears a Bruckner cycle with 37years and is related to the SOI with the cycle of 36.7 years.It is also found that it hasrelation to the globe temperature change (the correlation coefficient between them is0.41) and to the correlation distribution of SST in North Pacific,which is similar to thesea surface temperature anomalies pattern during the El Nino period.Therefore,the appearance of drought/flood pattern in 1991 may be related to theinherent climatic oscillation,such as the long-term variation for itself in the dryness/wetness pattern,the globe climate warming,and particularly,the intensification phaseof the ENSO events.