Freshwater in the Arctic Ocean 2010–2019

Abstract. The Arctic climate system is rapidly transitioning into a new regime with a reduction in the extent of sea ice, enhanced mixing in the ocean and atmosphere, and thus enhanced coupling within the ocean–ice–atmosphere system; these physical changes are leading to ecosystem changes in the Arctic Ocean. In this review paper, we assess one of the critically important aspects of this new regime, the variability of Arctic freshwater, which plays a fundamental role in the Arctic climate system by impacting ocean stratification and sea ice formation or melt. Liquid and solid freshwater exports also affect the global climate system, notably by impacting the global ocean overturning circulation. We assess how freshwater budgets have changed relative to the 2000–2010 period. We include discussions of processes such as poleward atmospheric moisture transport, runoff from the Greenland Ice Sheet and Arctic glaciers, the role of snow on sea ice, and vertical redistribution. Notably, sea ice cover has become more seasonal and more mobile; the mass loss of the Greenland Ice Sheet increased in the 2010s (particularly in the western, northern, and southern regions) and imported warm, salty Atlantic waters have shoaled. During 2000–2010, the Arctic Oscillation and moisture transport into the Arctic are in-phase and have a positive trend. This cyclonic atmospheric circulation pattern forces reduced freshwater content on the Atlantic–Eurasian side of the Arctic Ocean and freshwater gains in the Beaufort Gyre. We show that the trend in Arctic freshwater content in the 2010s has stabilized relative to the 2000s, potentially due to an increased compensation between a freshening of the Beaufort Gyre and a reduction in freshwater in the rest of the Arctic Ocean. However, large inter-model spread across the ocean reanalyses and uncertainty in the observations used in this study prevent a definitive conclusion about the degree of this compensation.

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Freshwater in the Arctic Ocean 2010–2019

10.5194/os-2020-113 ◽

2020 ◽

Author(s):

Amy Solomon ◽

Céline Heuzé ◽

Benjamin Rabe ◽

Sheldon Bacon ◽

Laurent Bertino ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Review Paper ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Climate System ◽

Arctic Climate ◽

The Arctic ◽

Global Ocean ◽

The Arctic Ocean

Abstract. The Arctic climate system is rapidly transitioning into a new regime with a reduction in the extent of sea ice, enhanced mixing in the ocean and atmosphere, and thus enhanced coupling within the ocean-ice-atmosphere system; these physical changes are leading to ecosystem changes in the Arctic Ocean. In this review paper, we assess one of the critically important aspects of this new regime, the variability of Arctic freshwater, which plays a fundamental role in the Arctic climate system by impacting ocean stratification and sea ice formation. Liquid and solid freshwater exports also affect the global climate system, notably by impacting the global ocean overturning circulation. In this review paper we assess to what extent observations during the 2010–2019 period are sufficient to estimate the Arctic freshwater budget with greater certainty than previous assessments and how this budget has changed relative to the 2000–2010 period. We include discussions of processes not included in previous assessments, such as run off from the Greenland Ice Sheet, the role of snow on sea ice, and vertical redistribution. We show that the trend in Arctic freshwater in the 2010s has stabilized relative to the 2000s due to an increased compensation between a freshening of the Beaufort Gyre and a reduction in freshwater in the Amerasian and Eurasian basins. Notably, the sea ice cover has become more seasonal and more mobile, the mass loss of the Greenland ice sheet has shifted from the western to the eastern part, and the import of subpolar waters into the Arctic has increased.

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Moisture transport from the Arctic: a characterization from a Lagrangian perspective

Cuadernos de Investigación Geográfica ◽

10.18172/cig.3477 ◽

2018 ◽

Vol 44 (2) ◽

pp. 659 ◽

Cited By ~ 2

Author(s):

M. Vázquez ◽

R. Nieto ◽

A. Drumond ◽

L. Gimeno

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Moisture Transport ◽

Hydrological Cycle ◽

Moisture Loss ◽

Lagrangian Model ◽

The Arctic ◽

Sea Ice Extent ◽

The Arctic Ocean ◽

Moisture Supply

The Arctic Ocean has suffered extreme reductions in sea ice in recent decades, and these observed changes suggest implications in terms of moisture transport. The Arctic region is a net sink of moisture in terms of the total hydrological cycle, however, its role as a moisture source for specific regions has not been extensively studied. Our results show that 80% of the moisture supply from the Arctic contributes to precipitation over itself, representing about 8% of the global moisture supply to the Arctic, the remaining 20% is distributed in the surrounding. A reduction in the sea ice extent could make the Arctic Ocean a slightly higher source of moisture to itself or to the surrounding areas. The analysis of the areas affected by Arctic moisture transport is important for establishing those areas vulnerable to change in a framework of a growing sea ice decline. To this end, the Lagrangian model FLEXPART was used in this work to establish the main sinks for the Arctic Ocean, focusing on the moisture transport from this region. The results suggest that most of the moisture loss occurs locally over the Arctic Ocean itself, especially in summer. Some moisture contribution from the Arctic Ocean to continental areas in North America and Eurasia is also noted in autumn and winter especially from Central Arctic, the East Siberian Sea, the Laptev, Kara, Barents, East Greenland and Bering Seas, and the Sea of Okhotsk.

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Light-absorbing impurities in Arctic snow

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-18807-2010 ◽

2010 ◽

Vol 10 (8) ◽

pp. 18807-18878 ◽

Cited By ~ 12

Author(s):

S. J. Doherty ◽

S. G. Warren ◽

T. C. Grenfell ◽

A. D. Clarke ◽

R. E. Brandt

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Greenland Ice Sheet ◽

Surface Energy Budget ◽

The Arctic ◽

Arctic Canada ◽

Near Surface ◽

Near Ultraviolet ◽

The Arctic Ocean ◽

Snow Samples

Abstract. Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005–2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity to BC sources. Individual samples of falling snow were collected on Svalbard, documenting the springtime decline of BC from March through May. Absorption Ångstrom exponents are 1.5–1.7 in Norway, Svalbard, and Western Russia, 2.1–2.3 elsewhere in the Arctic, and 2.5 in Greenland. Correspondingly, the estimated contribution to absorption by non-BC constituents in these regions is ~25%, 40%, and 50%, respectively. It has been hypothesized that when the snow surface layer melts some of the BC is left at the top of the snowpack rather than being carried away in meltwater. This process was observed in a few locations and would cause a positive feedback on snowmelt. The BC content of the Arctic atmosphere has declined markedly since 1989, according to the continuous measurements of near-surface air at Alert (Canada), Barrow (Alaska), and Ny-Ålesund (Svalbard). Correspondingly, the new BC concentrations for Arctic snow are somewhat lower than those reported by Clarke and Noone for 1983–1984, but because of methodological differences it is not clear that the differences are significant.

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Arctic Ocean sea ice snow depth evaluation and bias sensitivity in CCSM

The Cryosphere Discussions ◽

10.5194/tcd-7-1495-2013 ◽

2013 ◽

Vol 7 (2) ◽

pp. 1495-1532 ◽

Cited By ~ 6

Author(s):

B. A. Blazey ◽

M. M. Holland ◽

E. C. Hunke

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

System Model ◽

Arctic Climate ◽

The Arctic ◽

Blowing Snow ◽

Climate System Model ◽

The Arctic Ocean ◽

Ice Conditions

Abstract. Sea ice cover in the Arctic Ocean is a continued focus of attention. This study assesses the capability of hindcast simulations of the Community Climate System Model (CCSM) to reproduce observed snow depths and densities overlying the Arctic Ocean sea ice. The model is evaluated using measurements provided by historic Russian polar drift stations. Following the identification of seasonal biases produced in the simulations, the thermodynamic transfer through the snow – ice column is perturbed to determine model sensitivity to these biases. This study concludes that perturbations on the order of the observed biases result in modification of the annual mean conductive flux of 0.5 W m−2 relative to an unmodified simulation. The results suggest that the ice has a complex response to snow characteristics, with ice of different thicknesses producing distinct reactions. Consequently, we suggest that the inclusion of additional snow evolution processes such as blowing snow, densification, and seasonal changes in snow conductivity in sea ice models would increase the fidelity of the model with respect to the physical system. Moreover, our results suggest that simulated high latitude precipitation biases have important effects on the simulated ice conditions, resulting in impacts on the Arctic climate in general in large-scale climate.

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Impact of Poleward Moisture Transport from the North Pacific on the Acceleration of Sea Ice Loss in the Arctic since 2002

Journal of Climate ◽

10.1175/jcli-d-16-0461.1 ◽

2017 ◽

Vol 30 (17) ◽

pp. 6757-6769 ◽

Cited By ~ 24

Author(s):

H. J. Lee ◽

M. O. Kwon ◽

S.-W. Yeh ◽

Y.-O. Kwon ◽

W. Park ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

North Pacific ◽

Moisture Transport ◽

Arctic Sea Ice ◽

Specific Humidity ◽

The Arctic ◽

The North ◽

The Arctic Ocean ◽

The North Pacific

Abstract Arctic sea ice area (SIA) during late summer and early fall decreased substantially over the last four decades, and its decline accelerated beginning in the early 2000s. Statistical analyses of observations show that enhanced poleward moisture transport from the North Pacific to the Arctic Ocean contributed to the accelerated SIA decrease during the most recent period. As a consequence, specific humidity in the Arctic Pacific sector significantly increased along with an increase of downward longwave radiation beginning in 2002, which led to a significant acceleration in the decline of SIA in the Arctic Pacific sector. The resulting sea ice loss led to increased evaporation in the Arctic Ocean, resulting in a further increase of the specific humidity in mid-to-late fall, thus acting as a positive feedback to the sea ice loss. The overall set of processes is also found in a long control simulation of a coupled climate model.

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Arctic Sea Ice Decline Significantly Contributed to the Unprecedented Liquid Freshwater Accumulation in the Beaufort Gyre of the Arctic Ocean

Geophysical Research Letters ◽

10.1029/2018gl077901 ◽

2018 ◽

Vol 45 (10) ◽

pp. 4956-4964 ◽

Cited By ~ 17

Author(s):

Qiang Wang ◽

Claudia Wekerle ◽

Sergey Danilov ◽

Nikolay Koldunov ◽

Dmitry Sidorenko ◽

...

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Arctic Sea Ice ◽

The Arctic ◽

Beaufort Gyre ◽

Sea Ice Decline ◽

Arctic Sea ◽

The Arctic Ocean

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Response/feedback of the Arctic Ocean in the Northern Hemisphere climate system: the sea-level joker

10.5194/egusphere-egu2020-6908 ◽

2020 ◽

Author(s):

Claude Hillaire-Marcel ◽

Anne de Vernal ◽

Yanguang Liu

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Northern Hemisphere ◽

North Atlantic ◽

Climate System ◽

The Arctic ◽

Bering Strait ◽

The North ◽

The Arctic Ocean ◽

The Status

<p>The Arctic Ocean is a major player in the climate system of the Northern Hemisphere due to its role vs albedo, atmospheric pressure regimes, and thermohaline circulation. It shows large amplitude variability from millennial, to decadal and seasonal time scales. At millennial time scales, two drastically distinct regimes prevail primarily in relation with ocean volume and sea level (SL) changes: A modern like system, with a high SL when the Arctic Ocean shelves are submerged and Bering Strait is opened vs a glacial one, with a low SL, when shelves are emerged and partly glaciated and Bering Strait is closed. In the modern system, large submerged shelves result in high productivity, high sea-ice production rates and sea ice-rafting deposition in the Central Arctic. Moreover, a fully open Bering Strait, with SL at the present elevation, contributes about 40% of the freshwater budget of the Arctic Ocean (Woodgate & Aagaard, 2005, doi:10.1029/2004GL021747), and supports Si fluxes of about 20 kmol.s<sup>-1</sup> towards the Western Arctic (Torres-Vald&#233;s et al., 2013, doi:10.1002/jgrc.20063), thus impacting primary productivity. Under low SL conditions, the Arctic Ocean is linked exclusively to the North Atlantic, through practically a single gateway, that of Fram Strait. Sedimentation in the Central Arctic is then dominated ice-rafting deposition from icebergs, thus controlled by streaming and calving processes along surrounding ice sheets. Due to its shallowness (< 50 m), the Bering Strait gateway becomes effective at a very late stage of glacial to interglacial transitions but closes early during reverse climate trends. Sedimentary records from shelves North of Strait may provide information on the status of the gateway, so far, for the present interglacial. Clay minerals in cores from the northern Alaskan shelf (Ortiz et al., 2009, doi:10.1016/j.gloplacha.2009.03.020) and micropaleontological tracers from the Chukchi Sea southern shelf (present study) can be used to document the status of the gateway. Here, North Pacific microfossils transported by currents through the gateway demonstrate its full effectiveness at ca 6 ka BP, well after the insolation maximum of the early Holocene but when SL had reached its maximum postglacial elevation, with significant impacts on Arctic Ocean salinity, sea-ice cover and productivity.. This out-of-phase behavior of the Arctic Ocean may have impacted the North Atlantic and Northern Hemisphere climate system, as the openings and closings of Bering Strait constitute critical tipping points on this system, off out of phase with other parameters controlling more globally the climate of the Northern Hemisphere.</p>

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