Transient Increase in Arctic Deep-Water Formation and Ocean Circulation under Sea Ice Retreat

Bretones, Anaïs; Nisancioglu, Kerim H.; Jensen, Mari F.; Brakstad, Ailin; Yang, Shuting

doi:10.1175/jcli-d-21-0152.1

Cited by 12 publications

(11 citation statements)

References 51 publications

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“…We also note that no new regions of deep convection emerge in the Arctic Ocean during the 21st century in CESM-LE. However, if deep convection emerges in the Arctic Ocean in the future 17 , 18 this could become an important additional mechanism of overturning changes.…”

Section: Resultsmentioning

confidence: 99%

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Future strengthening of the Nordic Seas overturning circulation

et al. 2023

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The overturning circulation in the Nordic Seas involves the transformation of warm Atlantic waters into cold, dense overflows. These overflow waters return to the North Atlantic and form the headwaters to the deep limb of the Atlantic meridional overturning circulation (AMOC). The Nordic Seas are thus a key component of the AMOC. However, little is known about the response of the overturning circulation in the Nordic Seas to future climate change. Here we show using global climate models that, in contrast to the North Atlantic, the simulated density-space overturning circulation in the Nordic Seas increases throughout most of the 21st century as a result of enhanced horizontal circulation and a strengthened zonal density gradient. The increased Nordic Seas overturning is furthermore manifested in the overturning circulation in the eastern subpolar North Atlantic. A strengthened Nordic Seas overturning circulation could therefore be a stabilizing factor in the future AMOC.

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Section: Resultsmentioning

confidence: 99%

“…These results thus challenge the importance of open-ocean deep convection in setting the strength of the AMOC. Previous modeling efforts have, however, identified the northward shift of deep-convection sites as a possible source of future overturning changes in the Nordic Seas and Arctic Ocean 16 – 18 .…”

Section: Introductionmentioning

confidence: 99%

Future strengthening of the Nordic Seas overturning circulation

et al. 2023

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“…The Yermak Plateau, that used to be ice‐covered year‐round now experiences occasional ice‐free conditions and has repeatedly shown enhanced winter convection over the past decade (Athanase et al., 2020). This northward “shift” of the convection regions has been projected to occur under a warming climate (Bretones et al., 2022; Lique & Thomas, 2018). The ice‐edge retreat also contribute to increase air‐sea heat fluxes and water mass transformation along the boundary currents in the area (East Greenland Current, West Spitsbergen Current and Svalbard Branch) (Moore et al., 2022; Våge et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

Recent Convection Decline in the Greenland Sea: Insights From the Mercator Ocean System Over 2008–2020

2023

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We investigated wintertime convection evolution in recent years over the Greenland Sea. This area is a major location regarding dense water production and supply of the lower limb of the Atlantic Meridional Overturning Circulation, a key component of the global climate. Previous studies mentioned an increase in Greenland Sea wintertime convection intensity during the 2000s in comparison with the previous decade till 2015/2016. Here, we further document the ongoing oceanic changes within the Greenland Sea through the Mercator Ocean Physical System, an operational ocean model with data‐assimilation. The model has shown a large variability, a later start and a decline of convection in the Greenland Sea in recent years. In particular, the depth of the annual maximum mixed layer diminished by 52% between 2008–2014 and 2015–2020, from 1,168 to 559 m, over the convective area. This decline of the convection depth is corroborated with Argo float observations. Within the Greenland Sea, hydrographic changes especially the increasing temperature are associated with isopycnal deepening and stratification strengthening. The stratification is building up at a larger rate in the Boreas Basin compared to the Greenland Basin. The changes of the Greenland Sea hydrography in the model are in part related to Atlantic Water spreading over the Boreas Basin and the eastern part of the Greenland Basin. The model also indicates a decrease in the intensity of the gyre in accordance with the isopycnal deepening while local surface winds and fluxes do not exhibit significant trends nor significant interannual variations.

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“…Moreover, a weaker haline stratification in combination with a lack of sea ice and a strong increase in winter MLD, can in some areas lead to a switch to a North Atlantic style (Labrador, Greenland-Iceland-Norway basin) deep convection (Brodeau & Koenigk, 2016). Several recent works point toward a growing interest for the concept of Arctic Overturning Circulations (Bretones et al, 2022;Haine, 2021).…”

Section: Discussionmentioning

confidence: 99%

Changes in Arctic Stratification and Mixed Layer Depth Cycle: A Modeling Analysis

et al. 2022

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Oceanic transport toward the Arctic Ocean consists mostly of Atlantic Water (AW hereafter) being transported by the Norwegian Atlantic Current toward higher latitudes (Helland-Hansen & Nansen, 1909). At the entrance of the Barents Sea, the AW flow divides in two branches. One branch enters the Barents Sea where it can either be transformed into dense water and exits at depths as so-called Arctic Intermediate Water (Schauer et al., 1997), or melt ice and become part of the "estuarine" component of the Arctic Ocean (Eldevik & Nilsen, 2013;Rudels, 2016;Stigebrandt, 1981). The other AW branch forms the West Spitsbergen Current which further splits into two branches. One of these recirculates and heads South, and merges with the East Greenland Current, and the other enters the Arctic through Fram Strait. The latter branch can either melt ice, or subduct below the lighter colder and fresher layer of Arctic Water. This latter branch then follows a pathway along the continental slope North of Svalbard and Franz Josef Land toward the eastern Nansen Basin, slowly losing its properties (Bluhm et al., 2020;Timmermans & Marshall, 2020).

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Transient Increase in Arctic Deep-Water Formation and Ocean Circulation under Sea Ice Retreat

Cited by 12 publications

References 51 publications

Future strengthening of the Nordic Seas overturning circulation

Future strengthening of the Nordic Seas overturning circulation

Recent Convection Decline in the Greenland Sea: Insights From the Mercator Ocean System Over 2008–2020

Changes in Arctic Stratification and Mixed Layer Depth Cycle: A Modeling Analysis

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