On the Observed Relationships between Variability in Gulf Stream Sea Surface Temperatures and the Atmospheric Circulation over the North Atlantic

Wills, Samantha M.; Thompson, David W. J.; Ciasto, Laura M.

doi:10.1175/jcli-d-15-0820.1

Cited by 40 publications

(63 citation statements)

References 36 publications

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“…For example, research exploring the monthly variability of precipitation over Europe identified a significant contribution from evaporation over land (Zveryaev and Allan, ), which could imply preconditioning in terms of both soil moisture and periods of drought. The significant impact of the atmospheric teleconnections identified herein, together with the role of SST variability on convective activity in Europe, similar to recently noted interactions (Piazza et al ., ; Wills et al ., ), motivates further analysis to explore both the joint variability along with other drivers of atmospheric–oceanic variability over the region that may be more remote, such as El Niño/Southern Oscillation (ENSO: cf. Lee et al ., ; Allen et al ., ; Cook et al ., ; Molina et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Investigation of the temporal variability of thunderstorms in central and western Europe and the relation to large‐scale flow and teleconnection patterns

Piper

Kunz

Allen

et al. 2019

Quart J Royal Meteoro Soc

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The driving factors that influence the spatial and annual variability of thunderstorms across Europe are still poorly understood. Due to a lack of long‐term, reliable and consistent information about the occurrence of convective storms, a weather type classification has been developed that estimates thunderstorm probability from a combination of appropriate meteorological quantities on the mesoscale. Based on this approach, the temporal and spatial variability of convection‐favouring environments is investigated between 1958 and 2014 using a high‐resolution reanalysis dataset. To identify potential drivers for convective days, typical upper‐level flow patterns were deduced using a multivariate approach. Our results suggest a strong link between local‐scale thunderstorm activity and large‐scale flow and air mass properties, such as stability, moisture, or vertical lifting. For example, while all over central Europe the most prominent pattern is given by a southwesterly flow type over the respective area, distinct regional discrepancies regarding further favourable flow types are observed. The crucial role of large‐scale flow is further studied by assessing the relation between Northern Hemisphere teleconnection patterns and widespread convective activity. It is found that positive phases of the East Atlantic or Scandinavian patterns go along with a significant enhancement of convection‐favouring conditions in several European regions, which can be explained by anomalies in the large‐scale temperature and flow fields. Sea‐surface temperature over the Bay of Biscay likewise impacts the convective environment, with the largest positive effect over the western part of the study area.

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Section: Discussionmentioning

confidence: 97%

Investigation of the temporal variability of thunderstorms in central and western Europe and the relation to large‐scale flow and teleconnection patterns

Piper

Kunz

Allen

et al. 2019

Quart J Royal Meteoro Soc

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“…6e), in which the baroclinic vertical structure of the u response is evident. The significant positive u anomaly of 0.2-0.3 K extends up to 300 hPa and is accompanied by the ascending motion (Czaja and Blunt 2011;Smirnov et al 2015;Wills et al 2016), while the significant negative u anomaly of 0.2-0.3 K up to 600 hPa is coincident with the descending motion. The deeper extension of the diabatic heating than the cooling is consistent with the finding by Révelard et al (2016), who attributed the uneven vertical distribution of the heating and cooling to the primary cause of the nonlinearity in observed circulation response to the changes in the Kuroshio Extension front (Qiu et al 2014).…”

Section: Vertical Distribution Of the Responsementioning

confidence: 94%

“…However, Frankignoul et al (2001) found no evidence that the GS SST anomaly exerts a direct impact on the large-scale circulation. 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: 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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“…Thus, the sharp SST front plays an important role in the occurrence of European winter-time blockings (O'Reilly et al 2016). Using ERAInterim data, it was shown that warm SST anomalies in the Gulf Stream region can be connected to anomalous anticyclonic atmospheric circulation anomalies over the Gulf Stream extension several weeks before, advecting warm air northward across the (climatological) SST gradient (Wills et al 2016). A linearly independent anticyclonic anomaly south of Iceland can be found lagging these SST anomalies by 10-20 days and likely reflects the atmospheric response to the anomalous SST forcing.…”

mentioning

confidence: 99%

The role of local sea surface temperature pattern changes in shaping climate change in the North Atlantic sector

et al. 2018

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Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the wintertime response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model's atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum-or "warming hole"-in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of the local SST pattern changes on regions outside the North Atlantic is small in our setup.

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On the Observed Relationships between Variability in Gulf Stream Sea Surface Temperatures and the Atmospheric Circulation over the North Atlantic

Cited by 40 publications

References 36 publications

Investigation of the temporal variability of thunderstorms in central and western Europe and the relation to large‐scale flow and teleconnection patterns

Investigation of the temporal variability of thunderstorms in central and western Europe and the relation to large‐scale flow and teleconnection patterns

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

The role of local sea surface temperature pattern changes in shaping climate change in the North Atlantic sector

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