Role of Greenland Freshwater Anomaly in the Recent Freshening of the Subpolar North Atlantic

Dukhovskoy, Dmitry S.; Yashayaev, Igor; Proshutinsky, Andrey; Bamber, Jonathan; Bashmachnikov, Igor; Chassignet, Eric P.; Lee, C. M.; Tedstone, Andrew

doi:10.1029/2018jc014686

Cited by 66 publications

(80 citation statements)

References 82 publications

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“…Additional validation of these findings was conducted through comparison with results of tracer experiments employing a 0.08° (~4.5‐km horizontal resolution) HYbrid Coordinate Ocean Model (HYCOM) model. The model details and passive tracer calculations are provided in Dukhovskoy et al (; this special issue). Since 1993, site‐specific passive tracers were released continuously at the mouths of the Mackenzie River, East Eurasian Rivers (Kolyma, Lena, and Khatanga), West Eurasian Rivers (Pyasina, Enisey, Ob, Pechora, and Sev.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

et al. 2019

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Hydrographic data collected from research cruises, bottom-anchored moorings, driftingIce-Tethered Profilers, and satellite altimetry in the Beaufort Gyre region of the Arctic Ocean document an increase of more than 6,400 km 3 of liquid freshwater content from 2003 to 2018: a 40% growth relative to the climatology of the 1970s. This fresh water accumulation is shown to result from persistent anticyclonic atmospheric wind forcing accompanied by sea ice melt, a wind-forced redirection of Mackenzie River discharge from predominantly eastward to westward flow, and a contribution of low salinity waters of Pacific Ocean origin via Bering Strait. Despite significant uncertainties in the different observations, this study has demonstrated the synergistic value of having multiple diverse datasets to obtain a more comprehensive understanding of Beaufort Gyre freshwater content variability. For example, Beaufort Gyre Observational System (BGOS) surveys clearly show the interannual increase in freshwater content, but without satellite or Ice-Tethered Profiler measurements, it is not possible to resolve the seasonal cycle of freshwater content, which in fact is larger than the year-to-year variability, or the more subtle interannual variations. Plain Language AbstractThe Beaufort Gyre centered in the Canada Basin of the Arctic Ocean is the major reservoir of fresh water in the Arctic. The primary focus of this study is on quantifying variability and trends in liquid (water) and solid (sea ice) freshwater content in this region. The Beaufort Gyre Exploration Program was initiated in 2003 to synthesize results of historical data analysis, design and conduct long-term observations, and to provide information for numerical modeling under the umbrella of the FAMOS (Forum for Arctic Observing and Modeling Synthesis) project. The data collected from research cruises, moorings, Ice-Tethered Profiler observations, and satellite altimetry document an increase of more than 6,400 km 3 of liquid freshwater content from 2003 to 2018, a 40% growth relative to the climatology of the 1970s. This fresh water volume is comparable to the fresh water volume released to the sub-arctic seas during the Great Salinity Anomaly episode of the 1970s. Thus, since the 2000s, the stage has been set for another possible release of fresh water to lower latitudes with accompanying climate impacts, including changes to sea ice conditions, ocean circulation, and ecosystems of the Sub-Arctic similar to the influence of the Great Salinity Anomaly observed in the 1970s.

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Section: Discussionmentioning

confidence: 99%

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

et al. 2019

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“…As can be seen in Figures 11 and 16, runoff is included as a climatological mean based only on observations of river runoff. Dukhovskoy et al (2019) suggested that Greenland ice sheet and land ice melting, as compiled by Bamber et al (2012, 2018), is a potentially important source contributing to the recent freshening observed in the SPNA. Other studies, however, show that the freshwater source from Greenland ice sheet melting is relatively small, for example, as quantified in Haine et al (2015) or simulated in Böning et al (2016).…”

Section: Discussionmentioning

confidence: 99%

“…As all outflows from the Arctic Ocean lead to the SPNA and NSEA, it is expected that some of the associated freshwater will eventually be transported to these regions, for the SPNA to the western part in particular, which includes the Labrador Sea (LSEA). Furthermore, the Greenland ice sheet is losing mass at an accelerating rate (Bamber et al, 2012; Rignot et al, 2008; Trusel et al, 2018) providing additional freshwater into the SPNA and NSEA regions (Bamber et al, 2018; Dukhovskoy et al, 2019). Future climate change is expected to further increase the freshwater fluxes into both the Arctic and North Atlantic, as the result of an intensification of the water cycle, loss of sea ice, and glacial melting (Durack et al, 2012; Held & Soden, 2006; Jahn & Holland, 2013; Koenigk et al, 2007; Lau et al, 2013; Nummelin et al, 2016; Rennermalm et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Dominant Terms in the Freshwater and Heat Budgets of the Subpolar North Atlantic Ocean and Nordic Seas From 1992 to 2015

Tesdal

Haine

2020

JGR Oceans

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The Arctic and subarctic oceans exhibit distinct decadal variations in freshwater and heat content. We describe freshwater and heat budgets with the ECCOv4 reanalysis product and compare budget variability and mechanisms within the subpolar North Atlantic Ocean, Nordic Seas, and Labrador Sea from 1992 to 2015. For all regions, changes in freshwater content are largely anticorrelated with changes in heat content. Since 1995, the subpolar North Atlantic Ocean has undergone a decade of warming and salinification followed by ongoing cooling and freshening. The recent increase in freshwater content and the reduction in heat in the subpolar North Atlantic can largely be attributed to anomalous circulation of mean salinity and temperature, respectively. Interannual variability in heat and freshwater mostly corresponds to boundary fluxes from the subtropics. Meanwhile, the Nordic Seas have undergone an overall warming and salinification from the mid-1990s to 2015. Salinification is primarily driven by reduced sea ice flux through Fram Strait, while warming is due to changes in both sea surface heating and advective flux. In the last 5 years, Labrador Sea freshwater convergence remained unchanged, as increased inflow via the Baffin Island Current is balanced by increased outflow via the Labrador Current. Hence, the observed freshening of the Arctic Ocean is expected to be an increasingly important source of future freshwater increases in the subpolar North Atlantic. This stands in contrast to variability in freshwater flux from the subtropical North Atlantic, which is associated with variability in the Atlantic Meridional Overturning Circulation.

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“…2 and 3). Further, while the EGC can receive additional freshwater from enhanced Greenland ice-sheet melt, the volume of freshwater from ice sheet melt is small compared to Arctic freshwater sources, and cannot explain interannual variations in SPNA salinity 48 .…”

Section: Freshening Of the Eastern Subpolar Region In 2012-2016mentioning

confidence: 99%

Ocean circulation causes the largest freshening event for 120 years in eastern subpolar North Atlantic

et al. 2020

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The Atlantic Ocean overturning circulation is important to the climate system because it carries heat and carbon northward, and from the surface to the deep ocean. The high salinity of the subpolar North Atlantic is a prerequisite for overturning circulation, and strong freshening could herald a slowdown. We show that the eastern subpolar North Atlantic underwent extreme freshening during 2012 to 2016, with a magnitude never seen before in 120 years of measurements. The cause was unusual winter wind patterns driving major changes in ocean circulation, including slowing of the North Atlantic Current and diversion of Arctic freshwater from the western boundary into the eastern basins. We find that winddriven routing of Arctic-origin freshwater intimately links conditions on the North West Atlantic shelf and slope region with the eastern subpolar basins. This reveals the importance of atmospheric forcing of intra-basin circulation in determining the salinity of the subpolar North Atlantic.

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Role of Greenland Freshwater Anomaly in the Recent Freshening of the Subpolar North Atlantic

Cited by 66 publications

References 82 publications

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

Analysis of the Beaufort Gyre Freshwater Content in 2003–2018

Dominant Terms in the Freshwater and Heat Budgets of the Subpolar North Atlantic Ocean and Nordic Seas From 1992 to 2015

Ocean circulation causes the largest freshening event for 120 years in eastern subpolar North Atlantic

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