Projected squeezing of the wintertime North-Atlantic jet

Peings, Yannick; Cattiaux, Julien; Vavrus, Stephen J.; Magnúsdóttir, Guðrún

doi:10.1088/1748-9326/aacc79

Cited by 39 publications

(74 citation statements)

References 51 publications

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“…Focusing on the area of blocks identified using the DG index, the scaling law fairly well predicts the increase of A in the LENS (8.2% ± 1.1% model projection versus 9.3% ± 0.3% scaling law prediction) while overestimating the increase in the GFDL‐CM3 (10.5% ± 1% versus 15.9% ± 0.6%). In the North Atlantic winters, the jet becomes stronger and narrower in the LENS, as recently reported by Peings et al (). The jet becomes stronger but wider in the GFDL‐CM3, although the complex zonal wind profiles in this sector, due to the strong subtropical jet, complicate measurements of w (Figure S4).…”

Section: Resultssupporting

confidence: 81%

Size of the Atmospheric Blocking Events: Scaling Law and Response to Climate Change

Nabizadeh

Hassanzadeh

Yang

et al. 2019

Geophysical Research Letters

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Understanding the response of atmospheric blocking events to climate change has been of great interest in recent years. However, potential changes in the blocking area (size), which can affect the spatiotemporal characteristics of the resulting extreme events, have not received much attention. Using two large‐ensemble, fully coupled general circulation model (GCM) simulations, we show that the size of blocking events increases with climate change, particularly in the Northern Hemisphere (by as much as 17%). Using a two‐layer quasi‐geostrophic model and a dimensional analysis technique, we derive a scaling law for the size of blocking events, which shows that area mostly scales with width of the jet times the Kuo scale (i.e., the length of stationary Rossby waves). The scaling law is validated in a range of idealized GCM simulations. Predictions of this scaling law agree well with changes in blocking events' size under climate change in fully coupled GCMs in winters but not in summers.

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Section: Resultssupporting

confidence: 81%

Size of the Atmospheric Blocking Events: Scaling Law and Response to Climate Change

Nabizadeh

Hassanzadeh

Yang

et al. 2019

Geophysical Research Letters

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“…We first use a set of three metrics defined following Peings et al (2018). These metrics are similar to the metrics used by ZS17, albeit with slightly different definitions (e.g., selected levels and longitude-latitude boxes):…”

Section: Metricsmentioning

confidence: 99%

Drivers of the Northern Extratropical Eddy‐Driven Jet Change in CMIP5 and CMIP6 Models

Oudar

Cattiaux

Douville

2020

Geophysical Research Letters

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The wintertime midlatitude atmospheric circulation is evaluated in CMIP6 models. The biases have been reduced since CMIP5 although the low-level flow is still too zonal. CMIP5 and CMIP6 projections of 850 hPa zonal wind are then analyzed and are consistent under the RCP8.5 and the SSP5-8.5 scenarios, respectively. A poleward shift is identified in the Pacific, while a tripole structure is found in the North Atlantic: The zonal wind strengthens over Western Europe and decreases north and south. A multiple linear regression allows us to quantify the contribution of different drivers to the intermodel spread in zonal wind projections. It supports the importance of projected tropical warming and changes in the stratospheric vortex but also suggests a contribution of the asymmetry in the projected surface warming of the equatorial Pacific and of the present-day biases in the eddy-driven jet position. The North Atlantic warming hole plays a weaker role. Plain Language SummaryThe projection of the midlatitude atmospheric circulation is highly uncertain. Climate models exhibit a significant ensemble dispersion although some robust signals seem to emerge at the end of the 21st century: a poleward shift of the 850 hPa zonal wind in the Pacific and a strengthening over Northern Europe. This response is consistent between the former and current-generation global climate models. Several drivers have been proposed to explain this response. Here, it is confirmed that the amplified warming of the tropical high troposphere and variation of the stratospheric vortex play a more important role than the amplified warming over the Arctic. In addition, it is suggested that the West-East temperature gradient in the tropical Pacific and the biases of the jet position have a significant contribution, as opposed to the minimum warming in the North Atlantic.

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“…In the Northeast Atlantic, the impact of the increase in the upper tropospheric temperature gradient tends to win over of the reduction of the lower tropospheric temperature gradient, leading to a net strengthening of the storm track in the multi-model mean [125]. By modulating these temperature gradients, different storylines for the North Atlantic storm track can be considered in relation to the relative magnitude of the tropical upper tropospheric warming, Arctic warming and polar stratospheric cooling-a measure of stratospheric vortex strength [126,127]. In particular, the response in the strength of the stratospheric vortex can drive an NAO-like uncertainty in the North Atlantic atmospheric circulation [•64], with possible implications for European windiness [•63].…”

Section: Impacts On Windiness: the European Casementioning

confidence: 99%

“…2b), while it is not found for a weakening of the vortex [•63]. Additional storylines have been proposed in relation to the relative magnitude of the tropical versus Arctic warming, as "tropically amplified" models tend to be associated with a more squeezed and eastward extended jet into Europe [127]. It seems possible that this response could also favour enhanced European windiness, but it remains to be quantified.…”

Section: Impacts On Windiness: the European Casementioning

confidence: 99%

“…It seems possible that this response could also favour enhanced European windiness, but it remains to be quantified. Taken together, the relative amplitude of the tropical versus Arctic warming, and the change in the stratospheric vortex strength, show promise to characterise the uncertainty in key aspects of the North Atlantic jet response to climate change, such as its zonal extension and waviness [127].…”

Section: Impacts On Windiness: the European Casementioning

confidence: 99%

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Regional Climate Impacts of Future Changes in the Mid–Latitude Atmospheric Circulation: a Storyline View

Zappa

2019

Curr Clim Change Rep

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Purpose of Review Atmospheric circulation exerts a strong control on regional climate and extremes. However, projections of future circulation change remain uncertain, thus affecting the assessment of regional climate change. The purpose of this review is to describe some key cases where regional precipitation and windiness strongly depend on the mid-latitude atmospheric circulation response to warming, and summarise this into alternative plausible storylines of regional climate change. Recent Findings Recent research has enabled to better quantify the importance of dynamical aspects of climate change in shaping regional climate. The cold season precipitation response in Mediterranean-like regions is identified as one of the most susceptible impact-relevant aspects of regional climate driven by mid-latitude circulation changes. A circulation-forced drying might already be emerging in the actual Mediterranean, Chile and southwestern Australia. Increasing evidence indicates that distinct regional changes in atmospheric circulation and European windiness might unfold depending on the interplay of different climate drivers, such as surface warming patterns, sea ice loss and stratospheric changes. Summary The multi-model mean circulation response to warming tends to show washed-out signals due to the lack of robustness in the model projections, with implications for regional changes. To better communicate the information contained within these projections, it is useful to discuss regional climate change conditionally on alternative plausible storylines of atmospheric circulation change. As progress continues in understanding the factors driving the response of circulation to global warming, developing such storylines will provide end-to-end and physically self-consistent descriptions of plausible future unfoldings of regional climate change.

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Projected squeezing of the wintertime North-Atlantic jet

Cited by 39 publications

References 51 publications

Size of the Atmospheric Blocking Events: Scaling Law and Response to Climate Change

Size of the Atmospheric Blocking Events: Scaling Law and Response to Climate Change

Drivers of the Northern Extratropical Eddy‐Driven Jet Change in CMIP5 and CMIP6 Models

Regional Climate Impacts of Future Changes in the Mid–Latitude Atmospheric Circulation: a Storyline View

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