Recent Sea Ice Decline Did Not Significantly Increase the Total Liquid Freshwater Content of the Arctic Ocean

Abstract The freshwater stored in the Arctic Ocean is an important component of the global climate system. Currently the Arctic liquid freshwater content (FWC) has reached a record high since the beginning of the last century. In this study we use numerical simulations to investigate the impact of sea ice decline on the Arctic liquid FWC and its spatial distribution. The global unstructured-mesh ocean general circulation model Finite Element Sea Ice–Ocean Model (FESOM) with 4.5-km horizontal resolution in the Arctic region is applied. The simulations show that sea ice decline increases the FWC by freshening the ocean through sea ice meltwater and modifies upper ocean circulation at the same time. The two effects together significantly increase the freshwater stored in the Amerasian basin and reduce its amount in the Eurasian basin. The salinification of the upper Eurasian basin is mainly caused by the reduction in the proportion of Pacific Water and the increase in that of Atlantic Water (AW). Consequently, the sea ice decline did not significantly contribute to the observed rapid increase in the Arctic total liquid FWC. However, the changes in the Arctic freshwater spatial distribution indicate that the influence of sea ice decline on the ocean environment is remarkable. Sea ice decline increases the amount of Barents Sea branch AW in the upper Arctic Ocean, thus reducing its supply to the deeper Arctic layers. This study suggests that all the dynamical processes sensitive to sea ice decline should be taken into account when understanding and predicting Arctic changes.

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Attribution of the Recent Winter Sea Ice Decline over the Atlantic Sector of the Arctic Ocean*

Journal of Climate ◽

10.1175/jcli-d-15-0042.1 ◽

2015 ◽

Vol 28 (10) ◽

pp. 4027-4033 ◽

Cited By ~ 97

Author(s):

Doo-Sun R. Park ◽

Sukyoung Lee ◽

Steven B. Feldstein

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Environmental Changes ◽

Arctic Sea Ice ◽

The Arctic ◽

Positive Trend ◽

Ir Radiation ◽

Atlantic Sector ◽

Sea Ice Decline ◽

The Arctic Ocean

Abstract Wintertime Arctic sea ice extent has been declining since the late twentieth century, particularly over the Atlantic sector that encompasses the Barents–Kara Seas and Baffin Bay. This sea ice decline is attributable to various Arctic environmental changes, such as enhanced downward infrared (IR) radiation, preseason sea ice reduction, enhanced inflow of warm Atlantic water into the Arctic Ocean, and sea ice export. However, their relative contributions are uncertain. Utilizing ERA-Interim and satellite-based data, it is shown here that a positive trend of downward IR radiation accounts for nearly half of the sea ice concentration (SIC) decline during the 1979–2011 winter over the Atlantic sector. Furthermore, the study shows that the Arctic downward IR radiation increase is driven by horizontal atmospheric water flux and warm air advection into the Arctic, not by evaporation from the Arctic Ocean. These findings suggest that most of the winter SIC trends can be attributed to changes in the large-scale atmospheric circulations.

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Importance of Human-Induced Nitrogen Flux Increases for Simulated Arctic Warming

Journal of Climate ◽

10.1175/jcli-d-20-0180.1 ◽

2021 ◽

Vol 34 (10) ◽

pp. 3799-3819

Author(s):

Hyung-Gyu Lim ◽

Jong-Yeon Park ◽

John P. Dunne ◽

Charles A. Stock ◽

Sung-Ho Kang ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

The Arctic ◽

Biogeochemical Model ◽

Biological Feedback ◽

Arctic Warming ◽

The Arctic Ocean ◽

N Fluxes ◽

The Impact ◽

Chlorophyll Concentrations

AbstractHuman activities such as fossil fuel combustion, land-use change, nitrogen (N) fertilizer use, emission of livestock, and waste excretion accelerate the transformation of reactive N and its impact on the marine environment. This study elucidates that anthropogenic N fluxes (ANFs) from atmospheric and river deposition exacerbate Arctic warming and sea ice loss via physical–biological feedback. The impact of physical–biological feedback is quantified through a suite of experiments using a coupled climate–ocean–biogeochemical model (GFDL-CM2.1-TOPAZ) by prescribing the preindustrial and contemporary amounts of riverine and atmospheric N fluxes into the Arctic Ocean. The experiment forced by ANFs represents the increase in ocean N inventory and chlorophyll concentrations in present and projected future Arctic Ocean relative to the experiment forced by preindustrial N flux inputs. The enhanced chlorophyll concentrations by ANFs reinforce shortwave attenuation in the upper ocean, generating additional warming in the Arctic Ocean. The strongest responses are simulated in the Eurasian shelf seas (Kara, Barents, and Laptev Seas; 65°–90°N, 20°–160°E) due to increased N fluxes, where the annual mean surface temperature increase by 12% and the annual mean sea ice concentration decrease by 17% relative to the future projection, forced by preindustrial N inputs.

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Cryospheric Impacts of Soviet River Diversion Schemes

Annals of Glaciology ◽

10.3189/1984aog5-1-61-68 ◽

1984 ◽

Vol 5 ◽

pp. 61-68 ◽

Cited By ~ 4

Author(s):

T. Holt ◽

P. M. Kelly ◽

B. S. G. Cherry

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

River Discharge ◽

Large Scale ◽

Arctic Sea Ice ◽

The Arctic ◽

Sea Ice Concentration ◽

Ice Concentration ◽

The Arctic Ocean ◽

The Impact

Soviet plans to divert water from rivers flowing into the Arctic Ocean have led to research into the impact of a reduction in discharge on Arctic sea ice. We consider the mechanisms by which discharge reductions might affect sea-ice cover and then test various hypotheses related to these mechanisms. We find several large areas over which sea-ice concentration correlates significantly with variations in river discharge, supporting two particular hypotheses. The first hypothesis concerns the area where the initial impacts are likely to which is the Kara Sea. Reduced riverflow is associated occur, with decreased sea-ice concentration in October, at the time of ice formation. This is believed to be the result of decreased freshening of the surface layer. The second hypothesis concerns possible effects on the large-scale current system of the Arctic Ocean and, in particular, on the inflow of Atlantic and Pacific water. These effects occur as a result of changes in the strength of northward-flowing gradient currents associated with variations in river discharge. Although it is still not certain that substantial transfers of riverflow will take place, it is concluded that the possibility of significant cryospheric effects and, hence, large-scale climate impact should not be neglected.

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Intensification of the Atlantic Water Supply to the Arctic Ocean Through Fram Strait Induced by Arctic Sea Ice Decline

Geophysical Research Letters ◽

10.1029/2019gl086682 ◽

2020 ◽

Vol 47 (3) ◽

Cited By ~ 3

Author(s):

Qiang Wang ◽

Claudia Wekerle ◽

Xuezhu Wang ◽

Sergey Danilov ◽

Nikolay Koldunov ◽

...

Keyword(s):

Sea Ice ◽

Water Supply ◽

Arctic Ocean ◽

Atlantic Water ◽

Arctic Sea Ice ◽

The Arctic ◽

Fram Strait ◽

Sea Ice Decline ◽

Arctic Sea ◽

The Arctic Ocean

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Natural variability of the Arctic Ocean sea ice during the present interglacial

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2008996117 ◽

2020 ◽

Vol 117 (42) ◽

pp. 26069-26075

Author(s):

Anne de Vernal ◽

Claude Hillaire-Marcel ◽

Cynthia Le Duc ◽

Philippe Roberge ◽

Camille Brice ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Natural Variability ◽

Arctic Sea Ice ◽

The Arctic ◽

Lomonosov Ridge ◽

Arctic Sea ◽

The Arctic Ocean ◽

Open Question ◽

The Impact

The impact of the ongoing anthropogenic warming on the Arctic Ocean sea ice is ascertained and closely monitored. However, its long-term fate remains an open question as its natural variability on centennial to millennial timescales is not well documented. Here, we use marine sedimentary records to reconstruct Arctic sea-ice fluctuations. Cores collected along the Lomonosov Ridge that extends across the Arctic Ocean from northern Greenland to the Laptev Sea were radiocarbon dated and analyzed for their micropaleontological and palynological contents, both bearing information on the past sea-ice cover. Results demonstrate that multiyear pack ice remained a robust feature of the western and central Lomonosov Ridge and that perennial sea ice remained present throughout the present interglacial, even during the climate optimum of the middle Holocene that globally peaked ∼6,500 y ago. In contradistinction, the southeastern Lomonosov Ridge area experienced seasonally sea-ice-free conditions, at least, sporadically, until about 4,000 y ago. They were marked by relatively high phytoplanktonic productivity and organic carbon fluxes at the seafloor resulting in low biogenic carbonate preservation. These results point to contrasted west–east surface ocean conditions in the Arctic Ocean, not unlike those of the Arctic dipole linked to the recent loss of Arctic sea ice. Hence, our data suggest that seasonally ice-free conditions in the southeastern Arctic Ocean with a dominant Arctic dipolar pattern, may be a recurrent feature under “warm world” climate.

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Brine-Driven Eddies under Sea Ice Leads and Their Impact on the Arctic Ocean Mixed Layer

Journal of Physical Oceanography ◽

10.1175/2007jpo3620.1 ◽

2008 ◽

Vol 38 (1) ◽

pp. 146-163 ◽

Cited By ~ 10

Author(s):

Yoshimasa Matsumura ◽

Hiroyasu Hasumi

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Mixed Layer ◽

General Circulation ◽

Salt Transport ◽

Salt Flux ◽

The Arctic ◽

Theoretical Argument ◽

Ocean Mixed Layer ◽

The Arctic Ocean

Abstract Eddy generation induced by a line-shaped salt flux under a sea ice lead and associated salt transport are investigated using a three-dimensional numerical model. The model is designed to represent a typical condition for the wintertime Arctic Ocean mixed layer, where new ice formation within leads is known to be one of the primary sources of dense water. The result shows that along-lead baroclinic jets generate anticyclonic eddies at the base of the mixed layer, and almost all the lead-originated salt is contained inside these eddies. These eddies survive for over a month after closing of the lead and transport the lead-originated salt laterally. Consequently, the lead-origin salt settles only on the top of the halocline and is not used for increasing salinity of the mixed layer. Sensitivity experiments suggest that the horizontal scale of generated eddies depends only on the surface forcing and is proportional to the cube root of the total amount of salt input. This scaling of eddy size is consistent with a theoretical argument based on a linear instability theory. Parameterizing these processes would improve representation of the Arctic Ocean mixed layer in ocean general circulation models.

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How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-2647-2012 ◽

2012 ◽

Vol 12 (1) ◽

pp. 2647-2706 ◽

Cited By ~ 10

Author(s):

D. Durnford ◽

A. Dastoor ◽

A. Ryzhkov ◽

L. Poissant ◽

M. Pilote ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Atmospheric Mercury ◽

The Arctic ◽

Hudson Bay ◽

Arctic Circle ◽

Surface Level ◽

The Arctic Ocean ◽

Simulated Concentration ◽

The Impact

Abstract. An unknown fraction of mercury that is deposited onto snowpacks is revolatilized to the atmosphere. Determining the revolatilized fraction is important since mercury that enters the snowpack meltwater may be converted to highly toxic bioaccumulating methylmercury. In this study, we present a new dynamic physically-based snowpack/meltwater model for mercury that is suitable for large-scale atmospheric models for mercury. It represents the primary physical and chemical processes that determine the fate of mercury deposited onto snowpacks. The snowpack/meltwater model was implemented in Environment Canada's atmospheric mercury model GRAHM. For the first time, observed snowpack-related mercury concentrations are used to evaluate and constrain an atmospheric mercury model. We find that simulated concentrations of mercury in both snowpacks and the atmosphere's surface layer agree closely with observations. The simulated concentration of mercury in both in the top 30 cm and the top 150 cm of the snowpack, averaged over 2005–2009, is predominantly below 6 ng l−1 over land south of 66.5° N but exceeds 18 ng l−1 over sea ice in extensive areas of the Arctic Ocean and Hudson Bay. The average simulated concentration of mercury in snowpack meltwater runoff tends to be higher on the Russian/European side (>20 ng l−1) of the Arctic Ocean than on the Canadian side (<10 ng l−1). The correlation coefficient between observed and simulated monthly mean atmospheric surface-level GEM concentrations increased significantly with the inclusion of the new snowpack/meltwater model at two of the three stations (midlatitude, subarctic) studied and remained constant at the third (arctic). Oceanic emissions are postulated to produce the observed summertime maximum in concentrations of surface-level atmospheric GEM at Alert in the Canadian Arctic and to generate the summertime volatility observed in these concentrations at both Alert and Kuujjuarapik on subarctic Hudson Bay, Canada. We find that the fraction of deposited mercury that is revolatilized from snowpacks increases with latitude from 28% between 30 and 45° N, to 51% from 45 to 66.5° N, to 70% polewards of 66.5° N on an annual basis. Combining this latitudinal gradient with the latitudinally increasing coverage of snowpacks causes yearly net deposition as a fraction of gross deposition to decrease from 98% between 30 and 45° N to 85% between 45 and 66.5° N to 44% within the Arctic Circle. The yearly net deposition and net accumulation of mercury at the surface within the Arctic Circle north of 66.5° N are estimated at 153 and 117 Mg, respectively. We calculate that 63 and 45 Mg of mercury are deposited annually to the Arctic Ocean directly and indirectly via melting snowpacks, respectively. For terrestrial surfaces within the Arctic Circle, we find that 24 and 21 Mg of mercury are deposited annually directly and indirectly via melting snowpacks, respectively. Within the Arctic Circle, multi-season snowpacks gained an estimated average of 136 kg of mercury annually on land but lost an average of 133 kg annually over sea ice, possibly as a result of increased melting caused by rising temperatures. The developed snowpack/meltwater model can be used for investigating the impact of climate change on the snowpack/atmosphere exchange of mercury.

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Impact of Synthetic Arctic Argo-Type Floats in a Coupled Ocean–Sea Ice State Estimation Framework

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-19-0159.1 ◽

2020 ◽

Vol 37 (8) ◽

pp. 1477-1495 ◽

Cited By ~ 1

Author(s):

An T. Nguyen ◽

Patrick Heimbach ◽

Vikram V. Garg ◽

Victor Ocaña ◽

Craig Lee ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Circulation ◽

Quantitative Methods ◽

Numerical Models ◽

The Arctic ◽

Temporal Sampling ◽

Minimum Cover ◽

The Arctic Ocean ◽

Western Arctic

AbstractThe lack of continuous spatial and temporal sampling of hydrographic measurements in large parts of the Arctic Ocean remains a major obstacle for quantifying mean state and variability of the Arctic Ocean circulation. This shortcoming motivates an assessment of the utility of Argo-type floats, the challenges of deploying such floats due to the presence of sea ice, and the implications of extended times of no surfacing on hydrographic inferences. Within the framework of an Arctic coupled ocean–sea ice state estimate that is constrained to available satellite and in situ observations, we establish metrics for quantifying the usefulness of such floats. The likelihood of float surfacing strongly correlates with the annual sea ice minimum cover. Within the float lifetime of 4–5 years, surfacing frequency ranges from 10–100 days in seasonally sea ice–covered regions to 1–3 years in multiyear sea ice–covered regions. The longer the float drifts under ice without surfacing, the larger the uncertainty in its position, which translates into larger uncertainties in hydrographic measurements. Below the mixed layer, especially in the western Arctic, normalized errors remain below 1, suggesting that measurements along a path whose only known positions are the beginning and end points can help constrain numerical models and reduce hydrographic uncertainties. The error assessment presented is a first step in the development of quantitative methods for guiding the design of observing networks. These results can and should be used to inform a float network design with suggested locations of float deployment and associated expected hydrographic uncertainties.

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