Understanding the SAM influence on the South Pacific ENSO teleconnection
Understanding the SAM influence on the South Pacific ENSO teleconnection
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DOI：
10.1007/s00382-010-0905-0
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发表时间：
2011-04-01
期刊：
影响因子：
4.6
通讯作者：
Hines, Keith M.
中科院分区：
文献类型：
--
作者：
Fogt, Ryan L.;Bromwich, David H.;Hines, Keith M.
本文研究了厄尔尼诺南方涛动与南半球环模的关系，目的是了解各种强环模事件如何调制厄尔尼诺南方涛动与南太平洋(45A度-70A度S，150A度-70A度西经)的遥相关。重点是过去50年中多个月、多事件的变化。观察到了显著的(p<；0.10)关系，最明显的是在南半球夏季以及20世纪70年代和90年代。在大多数情况下，这种重要的关系是由拉尼娅(厄尔尼诺)事件与SAM的正(负)相比预期的更频繁地发生所带来的。南太平洋遥相关强度强烈依赖于SAM位相。只有当ENSO事件与弱SAM发生或当La Nia(El Nio)发生且SAM位相为正(负)时，才能发现显著的南太平洋遥相关。南太平洋ENSO遥相关中的这种调制与异常的ENSO和SAM瞬变涡动量通量的相互作用直接相关。在LaNiA/SAM+和El Nio/SAM-组合期间，太平洋异常的瞬变动量通量加强了中纬度的环流异常，从而改变了环流以维持ENSO遥相关。在LaNiA/SAM-和El Nio/SAM+的情况下，中纬度异常的瞬变涡旋相互对立，总体上降低了高纬度ENSO遥相关的强度。
The relationship between the El Nio Southern Oscillation (ENSO) and the Southern Hemisphere Annular Mode (SAM) is examined, with the goal of understanding how various strong SAM events modulate the ENSO teleconnection to the South Pacific (45A degrees-70A degrees S, 150A degrees-70A degrees W). The focus is on multi-month, multi-event variations during the last 50 years. A significant (p < 0.10) relationship is observed, most marked during the austral summer and in the 1970s and 1990s. In most cases, the significant relationship is brought about by La Nia (El Nio) events occurring with positive (negative) phases of the SAM more often than expected by chance. The South Pacific teleconnection magnitude is found to be strongly dependent on the SAM phase. Only when ENSO events occur with a weak SAM or when a La Nia (El Nio) occurs with a positive (negative) SAM phase are significant South Pacific teleconnections found. This modulation in the South Pacific ENSO teleconnection is directly tied to the interaction of the anomalous ENSO and SAM transient eddy momentum fluxes. During La Nia/SAM+ and El Nio/SAM- combinations, the anomalous transient momentum fluxes in the Pacific act to reinforce the circulation anomalies in the midlatitudes, altering the circulation in such a way to maintain the ENSO teleconnections. In La Nia/SAM- and El Nio/SAM+ cases, the anomalous transient eddies oppose each other in the midlatitudes, overall acting to reduce the magnitude of the high latitude ENSO teleconnection.