气候变化领域集成服务门户(CCPortal): The connection between the southern annular mode and a feature-based perspective on southern hemisphere midlatitude winter variability

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DOI	10.1175/JCLI-D-19-0224.1
	The connection between the southern annular mode and a feature-based perspective on southern hemisphere midlatitude winter variability
	Spensberger C.; Reeder M.J.; Spengler T.; Patterson M.
发表日期	2020
ISSN	0894-8755
起始页码	115
结束页码	129
卷号	33 期号:1
英文摘要	This article provides a reconciling perspective on the two main, but contradictory, interpretations of the southern annular mode (SAM). SAM was originally thought to characterize meridional shifts in the storm track across the entire hemisphere. This perspective was later questioned, and SAM was interpreted as a statistical artifact depending on the choice of base region for the principal component analysis. Neither perspective, however, fully describes SAM. We show that SAM cannot be interpreted in terms of midlatitude variability, as SAM merely modulates the most poleward part of the cyclone tracks and only marginally influences the distribution of other weather-related features of the storm track (e.g., position of jet axes and Rossby wave breaking). Instead, SAM emerges as the leading pattern of geopotential variability due to strong correlations of sea level pressure around the Antarctic continent. As SAM correlates strongly both with the pan-Antarctic mean temperature and the meridional heat flux through 658S, we hypothesize that SAM can be interpreted as a measure of the degree of the (de)coupling between Antarctica and the southern midlatitudes. As an alternative way of characterizing southern midlatitude variability, we seek domains in which the leading EOF patterns of both the geopotential and storm-track features yield a dynamically consistent picture. This approach is successful for the South Pacific. Here the leading variability patterns are closely related to the Pacific-South America pattern and point toward an NAO-like variability. © 2019 American Meteorological Society.
英文关键词	Heat flux; Mechanical waves; Sea level; Storms; Mean temperature; Sea level pressure; Southern Annular Mode; Southern Hemisphere; Statistical artifacts; Strong correlation; Variability patterns; Winter variability; Principal component analysis; atmospheric dynamics; climate variation; geopotential; heat flux; jet flow; midlatitude environment; Rossby wave; sea level pressure; Southern Hemisphere; storm track; winter; Antarctica; Pacific Ocean; Pacific Ocean (South)
语种	英语
来源期刊	Journal of Climate
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/171542
作者单位	Geophysical Institute, University of Bergen, Bjerknes Centre for Climate Research, Bergen, Norway; ARC Centre for Climate Extremes, Monash University, Melbourne, VIC, Australia; Department of Physics, University of Oxford, Oxford, United Kingdom
推荐引用方式 GB/T 7714	Spensberger C.,Reeder M.J.,Spengler T.,et al. The connection between the southern annular mode and a feature-based perspective on southern hemisphere midlatitude winter variability[J],2020,33(1).
APA	Spensberger C.,Reeder M.J.,Spengler T.,&Patterson M..(2020).The connection between the southern annular mode and a feature-based perspective on southern hemisphere midlatitude winter variability.Journal of Climate,33(1).
MLA	Spensberger C.,et al."The connection between the southern annular mode and a feature-based perspective on southern hemisphere midlatitude winter variability".Journal of Climate 33.1(2020).