气候变化领域集成服务门户(CCPortal): Wintertime southern hemisphere jet streams shaped by interaction of transient eddies with antarctic orography

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DOI	10.1175/JCLI-D-20-0153.1
	Wintertime southern hemisphere jet streams shaped by interaction of transient eddies with antarctic orography
	Patterson M.; Woollings T.; Bracegirdle T.J.; Lewis N.T.
发表日期	2020
ISSN	0894-8755
起始页码	10505
结束页码	10522
卷号	33 期号:24
英文摘要	The wintertime Southern Hemisphere extratropical circulation exhibits considerable zonal asymmetries.We investigate the roles of various surface boundary conditions in shaping the mean state using a semi-realistic, atmosphereonly climate model. We find, in agreement with previous literature, that tropical sea surface temperature (SST) patterns are an important contributor to the mean state, while midlatitude SSTs and sea ice extent play a smaller role. Our main finding is that Antarctic orography has a first-order effect on the structure of the midlatitude circulation. In the absence of Antarctic orography, equatorward eddy momentum fluxes associated with the orography are removed and hence convergence of eddy momentum in midlatitudes is reduced. This weakens the Indian Ocean jet, making Rossby wave propagation downstream to the South Pacific less favorable. Consequently, the flow stagnates over the mid- to high-latitude South Pacific and the characteristic split jet pattern is destroyed. Removing Antarctic orography also results in a substantial warming over East Antarctica partly because transient eddies are able to penetrate farther poleward, enhancing poleward heat transport. However, experiments in which a high-latitude cooling is applied indicate that these temperature changes are not the primary driver of circulation changes in the midlatitudes. Instead, we invoke a simple barotropic mechanism in which the orographic slope creates an effective potential vorticity gradient that alters the eddy momentum flux. © 2020 American Meteorological Society.
英文关键词	Climate models; Mechanical waves; Momentum; Ocean currents; Sea ice; Surface waters; Wave propagation; Circulation changes; Effective potentials; Extratropical circulation; Poleward heat transport; ROSSBY wave propagation; Sea surface temperature (SST); Surface boundary conditions; Temperature changes; Atmospheric movements; eddy; equation; jet stream; momentum transfer; orographic effect; potential vorticity; Rossby wave; sea surface temperature; Southern Hemisphere; wave propagation; winter; Antarctica; East Antarctica; Indian Ocean; 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/171036
作者单位	Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, United Kingdom; British Antarctic Survey, Cambridge, United Kingdom
推荐引用方式 GB/T 7714	Patterson M.,Woollings T.,Bracegirdle T.J.,et al. Wintertime southern hemisphere jet streams shaped by interaction of transient eddies with antarctic orography[J],2020,33(24).
APA	Patterson M.,Woollings T.,Bracegirdle T.J.,&Lewis N.T..(2020).Wintertime southern hemisphere jet streams shaped by interaction of transient eddies with antarctic orography.Journal of Climate,33(24).
MLA	Patterson M.,et al."Wintertime southern hemisphere jet streams shaped by interaction of transient eddies with antarctic orography".Journal of Climate 33.24(2020).