北极涛动与南极涛动的协同变率

摘要

北极涛动和南极涛动是调节全球中高纬度年际气候变率的主要因子.目前已有大量研究分别针对其变率、机理及其对区域气候的影响,然而对北极涛动和南极涛动之间的协同变化特征和机理仍然认识不清,限制了对南北半球气候变化相互作用的理解.研究北极涛动和南极涛动指数之间的差值与它们的和来讨论二者之间的反相与同相变化.结果表明,北极涛动与南极涛动之间的反相变化主要受到北极涛动异常的影响,南北半球之间气候带的移动及其伴随着北极涛动异常可能是导致二者出现反相变化的主要原因.北极涛动和南极涛动之间的同相变化对应于两个半球中纬度高压区的同相变化,这可能是两个半球哈德莱环流增强导致两个涛动出现同相变化.基于树轮重建的北极涛动和南极涛动能较好地恢复低频变化(如年代际变率),但对重建其高频变率(如年际变率)方面的效力不足.%Arctic Oscillation(AO)and Antarctic Oscillation are the two most important climate pat-terns that modulate interannual climate variability of middle and high latitudes of both hemispheres. Numerous studies have been conducted on the variability and mechanisms of AO and AAO as well as their linkages with regional climate anomalies.However,little attention has been paid on their co-vari-ability, which can shed lights on the interactions between inter-hemispheric climate changes.This study calculated the residuals and plus between AO and AAO to account for the in-phase and anti-phase variations between them.We found that the in-phase changes between AO and AAO are associ-ated with anomalies in AO changes,which may be caused by the inter-hemispheric shifts of the climate zones.The anti-phase changes between AO and AAO are associated with the in-phase changes of the pressures of the middle latitudes.This indicates that the enhancement the Hadley Cell contributes to the in-phase changes between them.The tree-ring based reconstructions of AO and AAO can well re-cord their long-term patterns,such as the interdecadal variability,but have difficulties in recording the short-term changes,such as the interannual variability.