The influence of the Gulf Stream on wintertime European blocking

O’Reilly, Christopher; Minobe, Shoshiro; Kuwano-Yoshida, Akira

doi:10.1007/s00382-015-2919-0

Cited by 71 publications

(82 citation statements)

References 90 publications

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“…In contrast, Wills et al (2016) identified the significant transient atmospheric circulation responses that lag the SST anomalies in the GS extension by several weeks, with the pattern of response characterized by the anomalous low (high) sea level pressure (SLP) over the GS region (south of Iceland). Similarly, O'Reilly et al (2017) found the northward shift of the North Atlantic eddy-driven jet and the increase in European blocking frequency in response to the GS SST front (see also O'Reilly et al 2016).…”

Section: Introductionmentioning

confidence: 76%

“…The change in transient eddy activity can strengthen the formation of a blocking ridge through the anomalous convergence of the eddy vorticity flux (Hoskins and Karoly 1981;Hoskins et al 1983;Hendon and Hartmann 1982;Peng and Whitaker 1999;Seo et al 2014;O'Reilly et al 2016). To quantify the role of the barotropic transient eddy feedback, we focus on the upper-level flow and calculate the Z 250 tendency solely caused by anomalous vorticity flux convergence Z HF t from a quasigeostrophic potential vorticity equation (e.g., Lau and Nath 1990), ›Z 250 ›t…”

Section: A High-frequency Dynamicsmentioning

confidence: 99%

“…In the North Atlantic, the largest surface heat flux and its strongest interannual variability are found over the Gulf Stream (GS). The variations in the location and strength of the GS modify the cyclogenesis and the North Atlantic storm track (Cione et al 1993;Booth et al 2012;Small et al 2014), potentially influencing the broader-scale atmospheric and climate variability (Minobe et al 2008;O'Reilly et al 2016O'Reilly et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

“…Tropical influence is removed based on the linear regression on the leading principal components of the tropical Indo-Pacific SST and tropical Atlantic SST. Piazza et al 2016) but also the low-frequency atmospheric circulation far downstream (Peings and Magnusdottir 2014;O'Reilly et al 2016). The diabatic forcing associated with an SST anomaly initiates a baroclinic adjustment in the atmosphere near the forcing region (Hoskins and Karoly 1981;Li and Conil 2003;Ferreira and Frankignoul 2005), which is linear about the sign and size of the SST anomaly ).…”

mentioning

confidence: 99%

“…Furthermore, the size and scale of the SST anomaly are too large and broad, respectively (e.g., 78C in Deser et al 2004). More recent GS-centric studies spatially smooth the GS SST front (Minobe et al 2008;Kuwano-Yoshida et al 2010;Small et al 2014;O'Reilly et al 2016;Piazza et al 2016), but the resulting SST anomalies are also too large (e.g., 668C is used in Small et al 2014) compared to the observed range of 618C inferred from Fig. 1.…”

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confidence: 99%

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On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

et al. 2017

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The North Atlantic atmospheric circulation response to the meridional shifts of the Gulf Stream (GS) path is examined using a large ensemble of high-resolution hemispheric-scale Weather Research and Forecasting Model simulations. The model is forced with a broad range of wintertime sea surface temperature (SST) anomalies derived from a lag regression on a GS index. The primary result of the model experiments, supported in part by an independent analysis of a reanalysis dataset, is that the large-scale quasi-steady North Atlantic circulation response is remarkably nonlinear about the sign and amplitude of the SST anomaly chosen over a wide range of GS shift scenarios. The nonlinear response prevails over the weak linear response and resembles the negative North Atlantic Oscillation (NAO), the leading intrinsic mode of variability in the model and the observations. Further analysis of the associated dynamics reveals that the nonlinear responses are accompanied by the shift of the North Atlantic eddy-driven jet, which is reinforced, with nearly equal importance, by the high-frequency transient eddy feedback and the low-frequency wave-breaking events. Additional sensitivity simulations confirm that the nonlinearity of the circulation response is a robust feature found over the broad parameter space encompassing not only the varied SST but also the absence/presence of tropical influence, the varying lateral boundary conditions, and the initialization scheme. The result highlights the fundamental importance of the intrinsically nonlinear transient eddy dynamics and the eddy-mean flow interactions in generating the nonlinear downstream response to the meridional shifts in the Gulf Stream.

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Section: Introductionmentioning

confidence: 76%

Section: A High-frequency Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

et al. 2017

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Atlantic near‐term climate variability and the role of a resolved Gulf Stream

Siqueira

Kirtman

2016

Geophysical Research Letters

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There is a continually increasing demand for near‐term (i.e., lead times up to a couple of decades) climate information. This demand is partly driven by the need to have robust forecasts and is partly driven by the need to assess how much of the ongoing climate change is due to natural variability and how much is due to anthropogenic increases in greenhouse gases or other external factors. Here we discuss results from a set of state‐of‐the‐art climate model experiments in comparison with observational estimates that show that an assessment of predictability requires models that capture the variability of major oceanic fronts, which are, at best, poorly resolved and may even be absent in the near‐term prediction of Intergovernmental Panel on Climate Change class models. This is the first time that air‐sea interactions associated with resolved Gulf Stream sea surface temperature have been identified in the context of a state‐of‐the‐art global coupled climate model with inferred near‐term predictability.

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Decomposition of the Mean Barotropic Transport in a High‐Resolution Model of the North Atlantic Ocean

Wang

Claus

Greatbatch

et al. 2017

Geophysical Research Letters

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We show how a barotropic shallow water model can be used to decompose the mean barotropic transport from a high‐resolution ocean model based on the vertically averaged momentum equations. We apply the method to a high‐resolution model of the North Atlantic for which the local vorticity budget is both noisy and dominated by small spatial scales. The shallow water model acts as an effective filter and clearly reveals the transport driven by each term. The potential energy (joint effect of baroclinicity and bottom relief) term is the most important for driving transport, including in the northwest corner, while mean flow advection is important for driving transport along f/H contours around the Labrador Sea continental slope. Both the eddy momentum flux and the mean flow advection terms drive significant transport along the pathway of the Gulf Stream and the North Atlantic Current.

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The influence of the Gulf Stream on wintertime European blocking

Abstract: 24Wintertime blocking is responsible for extended periods of anomalously cold and dry 25 weather over Europe. In this study, the influence of the Gulf Stream sea surface temperature 26 (SST) front on wintertime European blocking is investigated using a reanalysis dataset and a

Cited by 71 publications

References 90 publications

On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

On the Predominant Nonlinear Response of the Extratropical Atmosphere to Meridional Shifts of the Gulf Stream

Atlantic near‐term climate variability and the role of a resolved Gulf Stream

Decomposition of the Mean Barotropic Transport in a High‐Resolution Model of the North Atlantic Ocean

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