Investigation of the atmospheric mechanisms related to the autumn sea ice and winter circulation link in the Northern Hemisphere

King, Martin P.; Hell, Momme C.; Keenlyside, Noel

doi:10.1007/s00382-015-2639-5

Cited by 89 publications

(87 citation statements)

References 26 publications

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“…These changes are followed by downward propagation of anomalies that impact transient-eddy feedback at the upper troposphere, helping to settle and maintain the winter NAO at surface. Our results are in general agreement with the observational analysis by King et al (2015). Targeted modeling efforts are required to support the teleconnection dynamics and fully establish causality links in response to November SIC/ BK anomalies.…”

Section: Discussionsupporting

confidence: 80%

On the Predictability of the Winter Euro-Atlantic Climate: Lagged Influence of Autumn Arctic Sea Ice

et al. 2015

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International audienceSatellite-derived sea ice concentration (SIC) and reanalyzed atmospheric data are used to explore the predictability of the winter Euro-Atlantic climate resulting from autumn SIC variability over the Barents– Kara Seas region (SIC/BK). The period of study is 1979/80–2012/13. Maximum covariance analyses show that the leading predictand is indistinguishable from the North Atlantic Oscillation (NAO). The leading covari-ability mode between September SIC/BK and winter North Atlantic–European sea level pressure (SLP) is not significant, indicating that no empirical prediction skill can be achieved. The leading covariability mode with either October or November SIC/BK is moderately significant (significance levels ,10%), and both predictor fields yield a cross-validated NAO correlation of 0.3, suggesting some empirical prediction skill of the winter NAO index, with sea ice reduction in the Barents–Kara Seas being accompanied by a negative NAO phase in winter. However, only November SIC/BK provides significant cross-validated skill of winter SLP, surface air temperature, and precipitation anomalies over the Euro-Atlantic sector, namely in southwestern Europe. Statistical analysis suggests that November SIC/BK anomalies are associated with a Rossby wave train–like anomaly across Eurasia that affects vertical wave activity modulating the stratospheric vortex strength, which is then followed by downward propagation of anomalies that impact transient-eddy activity in the upper troposphere, helping to settle and maintain the NAO-like pattern at surface. This stratospheric pathway is not detected when using October SIC/BK anomalies. Hence, only November SIC/BK, with a one-month lead time, could be considered as a potential source of regional predictability

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Section: Discussionsupporting

confidence: 80%

On the Predictability of the Winter Euro-Atlantic Climate: Lagged Influence of Autumn Arctic Sea Ice

et al. 2015

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“…Last, the AMOC variability is also accompanied by sea ice changes (Mahajan et al 2011;GF12;Allison et al 2015;Zhang 2015). The sea ice variability has a major influence on the surface heat fluxes and it may also influence the North Atlantic Oscillation (Deser et al 2007;Strong et al 2009;Screen et al 2013) via the modulation of the stratospheric polar vortex (King et al 2015;García-Serrano et al 2015), or via the changes of transient eddies downstream of the North Atlantic storm track (García-Serrano et al 2015;García-Serrano and Frankignoul 2016). The AMOC impacts on sea ice might therefore also contribute to the atmospheric response to the AMOC.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms Determining the Winter Atmospheric Response to the Atlantic Overturning Circulation

et al. 2016

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In climate models, an intensification of the Atlantic meridional overturning circulation (AMOC) precedes a warming in the North Atlantic subpolar basin by a few years. In the IPSL-CM5A-LR model, this warming may explain the atmospheric response to the AMOC observed in winter, which resembles a negative phase of the North Atlantic Oscillation (NAO). To firmly establish the causality links between the ocean and the atmosphere and illustrate the underlying mechanisms in this model, ensembles of atmosphere-only simulations are conducted, prescribing the SST and sea ice anomalies that follow an AMOC intensification. In late winter, the North Atlantic SST and sea ice anomalies drive atmospheric circulation anomalies similar to those found in the coupled model. Simulations only driven by the SST anomalies related to the AMOC show that the largest oceanic influence is due to the warm subpolar SST anomaly, which enhances the oceanic heat release and decreases the lower-tropospheric baroclinicity in the region of maximum eddy growth, resulting in a weaker meridional eddy heat flux in the atmosphere. The transient eddy feedback leads to a negative NAO-like response. An AMOC intensification is also followed by less sea ice over the Labrador Sea and more sea ice over the Nordic seas. The simulations with full boundary forcing suggest that such anomalies act to strengthen both the poleward momentum flux and the upward heat flux into the polar stratosphere and lead to a stratospheric warming, which then reinforces the negative NAO signal in late winter.

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“…Novel methods to distinguish between statistical and causal relationships 68 , the application of artificial intelligence such as evolutionary algorithms 69 and a Bayesian hierarchical model approach may enable progress. Evidence for a variety of mid-latitude responses to Arctic warming is beginning to emerge [28][29][30][31][32][33][34][35][36][37][38] . Linkage mechanisms vary with season, region and system state, and they include both thermodynamic and dynamical processes.…”

Section: Living With An Uncertain Climate Systemmentioning

confidence: 99%

“…Together these factors make linkage attribution challenging. Many previous data and modelling analyses start with straightforward Arctic changes using, for example, diminished sea ice, and at least implicitly assume quasi-linear, sufficient causal connections 5,7,[25][26][27][28][29][30][31][32][33][34][35][36][37] . While this approach has been helpful in elucidating relevant linkage mechanisms, we provide a view that at the system level, multiple processes can mask simple cause and effect.…”

Section: Living With An Uncertain Climate Systemmentioning

confidence: 99%

Nonlinear response of mid-latitude weather to the changing Arctic

et al. 2016

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Investigation of the atmospheric mechanisms related to the autumn sea ice and winter circulation link in the Northern Hemisphere

Cited by 89 publications

References 26 publications

On the Predictability of the Winter Euro-Atlantic Climate: Lagged Influence of Autumn Arctic Sea Ice

On the Predictability of the Winter Euro-Atlantic Climate: Lagged Influence of Autumn Arctic Sea Ice

Mechanisms Determining the Winter Atmospheric Response to the Atlantic Overturning Circulation

Nonlinear response of mid-latitude weather to the changing Arctic

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