气候变化领域集成服务门户(CCPortal): The different stratospheric influence on cold-extremes in Eurasia and North America

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DOI	10.1038/s41612-018-0054-4
	The different stratospheric influence on cold-extremes in Eurasia and North America
	Kretschmer M.; Cohen J.; Matthias V.; Runge J.; Coumou D.
发表日期	2018
ISSN	23973722
卷号	1 期号:1
英文摘要	The stratospheric polar vortex can influence the tropospheric circulation and thereby winter weather in the mid-latitudes. Weak vortex states, often associated with sudden stratospheric warmings (SSW), have been shown to increase the risk of cold-spells especially over Eurasia, but its role for North American winters is less clear. Using cluster analysis, we show that there are two dominant patterns of increased polar cap heights in the lower stratosphere. Both patterns represent a weak polar vortex but they are associated with different wave mechanisms and different regional tropospheric impacts. The first pattern is zonally symmetric and associated with absorbed upward-propagating wave activity, leading to a negative phase of the North Atlantic Oscillation (NAO) and cold-air outbreaks over northern Eurasia. This coupling mechanism is well-documented in the literature and is consistent with the downward migration of the northern annular mode (NAM). The second pattern is zonally asymmetric and linked to downward reflected planetary waves over Canada followed by a negative phase of the Western Pacific Oscillation (WPO) and cold-spells in Central Canada and the Great Lakes region. Causal effect network (CEN) analyses confirm the atmospheric pathways associated with this asymmetric pattern. Moreover, our findings suggest the reflective mechanism to be sensitive to the exact region of upward wave-activity fluxes and to be state-dependent on the strength of the vortex. Identifying the causal pathways that operate on weekly to monthly timescales can pave the way for improved sub-seasonal to seasonal forecasting of cold spells in the mid-latitudes. © 2018, The Author(s).
语种	英语
scopus关键词	atmospheric circulation; cold wave; extreme event; midlatitude environment; polar vortex; stratosphere; sudden stratospheric warming; winter; Eurasia; North America
来源期刊	npj Climate and Atmospheric Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/178157
作者单位	Potsdam Institute for Climate Impact Research, Earth System Analysis, Potsdam, Germany; Department of Physics, University of Potsdam, Potsdam, Germany; Atmospheric and Environmental Research, Lexington, MA, United States; German Aerospace Center, Institute of Data Science, Jena, Germany; Department of Water and Climate Risk, Institute for Environmental Studies (IVM), VU University Amsterdam, Amsterdam, Netherlands
推荐引用方式 GB/T 7714	Kretschmer M.,Cohen J.,Matthias V.,et al. The different stratospheric influence on cold-extremes in Eurasia and North America[J],2018,1(1).
APA	Kretschmer M.,Cohen J.,Matthias V.,Runge J.,&Coumou D..(2018).The different stratospheric influence on cold-extremes in Eurasia and North America.npj Climate and Atmospheric Science,1(1).
MLA	Kretschmer M.,et al."The different stratospheric influence on cold-extremes in Eurasia and North America".npj Climate and Atmospheric Science 1.1(2018).