ENSO对云南地区降水影响的年代际变化

通过对云南地区近50年的降水与尼诺3区的海面温度(以下简称SST)的相关性研究发现,同期或是前期的SST均与该地区的降水存在一定的相关关系,如云南地区初夏降水与前期SST呈负相关关系,而秋季降水与前期SST呈正相关关系,即在ElNino(LaNina)年,该地区初夏降水容易偏少(多),而秋季降水容易偏多(少),整个地区雨季有后(前)移的可能性。因此我们认为,ENS0对云南降水的影响主要表现为云南雨季起讫的早晚。同时发现,这种影响存在明显的年代际变化特征,即云南地区初夏和秋季降水与前期SST的相关关系在1970年代中期到1980年代末期这段时期表现得尤为显著,之前或之后这种相关关系都没有通过显著性检验。

THE INFLUENCE OF ENSO EVENTS UPON YUNNAN PRECIPITATION AND ITS INTERDECADAL VARIATIONS

Results of an analysis show that during the recent 50 years there is an evident correlation between the precipitation of Yunnan and the sea surface temperature (SST) over the eastern equatorial Pacific. For example,a strong positive correlation appears between the previous SST and the autumn precipitation of Yunnan,whereas there is a strong negative correlation between SST and the earlier summer precipitation. It shows that in the years of El Nino (La Nina),the earlier summer precipitation of Yunnan is less (more) than normal but the autumn precipitation is more (less) than normal and the rainy season of Yunnan begins later (earlier) than normal. So in our opinion,this is the main influence of ENSO events upon Yunnan precipitation and it also associates with some characteristics of interdecadal variation. For instance,the correlation between the precipitation of Yunnan and SST is remarkable during the period from the middle of 1970's to the end of 1980's,but the correlation is weak out of this period.