Evidence for an increasing role of ocean heat in Arctic winter sea ice growth

AbstractWe investigate how sea ice decline in summer and warmer ocean and surface temperatures in winter affect sea ice growth in the Arctic. Sea ice volume changes are estimated from satellite observations during winter from 2002 to 2019 and partitioned into thermodynamic growth and dynamic volume change. Both components are compared to validated sea ice-ocean models forced by reanalysis data to extend observations back to 1980 and to understand the mechanisms that cause the observed trends and variability. We find that a negative feedback driven by the increasing sea ice retreat in summer yields increasing thermodynamic ice growth during winter in the Arctic marginal seas eastward from the Laptev Sea to the Beaufort Sea. However, in the Barents and Kara Seas, this feedback seems to be overpowered by the impact of increasing oceanic heat flux and air temperatures, resulting in negative trends in thermodynamic ice growth of -2 km3month-1yr-1 on average over 2002-2019 derived from satellite observations.

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Impact of Winter Ural Blocking on Arctic Sea Ice: Short-Time Variability

Journal of Climate ◽

10.1175/jcli-d-17-0194.1 ◽

2018 ◽

Vol 31 (6) ◽

pp. 2267-2282 ◽

Cited By ~ 12

Author(s):

Xiaodan Chen ◽

Dehai Luo ◽

Steven B. Feldstein ◽

Sukyoung Lee

Keyword(s):

Heat Flux ◽

Sea Ice ◽

Sensible Heat Flux ◽

Reanalysis Data ◽

Arctic Sea Ice ◽

Time Variability ◽

Sea Ice Concentration ◽

Arctic Sea ◽

Barents And Kara Seas ◽

The Impact

Using daily reanalysis data from 1979 to 2015, this paper examines the impact of winter Ural blocking (UB) on winter Arctic sea ice concentration (SIC) change over the Barents and Kara Seas (BKS). A case study of the sea ice variability in the BKS in the 2015/16 and 2016/17 winters is first presented to establish a link between the BKS sea ice variability and UB events. Then the UB events are classified into quasi-stationary (QUB), westward-shifting (WUB), and eastward-shifting (EUB) UB types. It is found that the frequency of the QUB events increases significantly during 1999–2015, whereas the WUB events show a decreasing frequency trend during 1979–2015. Moreover, it is shown that the variation of the BKS-SIC is related to downward infrared radiation (IR) and surface sensible and latent heat flux changes due to different zonal movements of the UB. Calculations show that the downward IR is the main driver of the BKS-SIC decline for QUB events, while the downward IR and surface sensible heat flux make comparable contributions to the BKS-SIC variation for WUB and EUB events. The SIC decline peak lags the QUB and EUB peaks by about 3 days, though QUB and EUB require lesser prior SIC. The QUB gives rise to the largest SIC decline likely because of its longer persistence, whereas the BKS-SIC decline is relatively weak for the EUB. The WUB is found to cause a SIC decline during its growth phase and an increase during its decay phase. Thus, the zonal movement of the UB has an important impact on the SIC variability in BKS.

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Interannual variability in Transpolar Drift ice thickness and potential impact of Atlantification

10.5194/tc-2020-305 ◽

2020 ◽

Author(s):

H. Jakob Belter ◽

Thomas Krumpen ◽

Luisa von Albedyll ◽

Tatiana A. Alekseeva ◽

Sergei V. Frolov ◽

...

Keyword(s):

Time Series ◽

Sea Ice ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Thickness ◽

Fram Strait ◽

Ice Growth ◽

Arctic Sea ◽

Transpolar Drift ◽

The Impact

Abstract. Changes in Arctic sea ice thickness are the result of complex interactions of the dynamic and variable ice cover with atmosphere and ocean. Most of the sea ice exits the Arctic Ocean through Fram Strait, which is why long-term measurements of ice thickness at the end of the Transpolar Drift provide insight into the integrated signals of thermodynamic and dynamic influences along the pathways of Arctic sea ice. We present an updated time series of extensive ice thickness surveys carried out at the end of the Transpolar Drift between 2001 and 2020. Overall, we see a more than 20 % thinning of modal ice thickness since 2001. A comparison with first preliminary results from the international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) shows that the modal summer thickness of the MOSAiC floe and its wider vicinity are consistent with measurements from previous years. By combining this unique time series with the Lagrangian sea ice tracking tool, ICETrack, and a simple thermodynamic sea ice growth model, we link the observed interannual ice thickness variability north of Fram Strait to increased drift speeds along the Transpolar Drift and the consequential variations in sea ice age and number of freezing degree days. We also show that the increased influence of upward-directed ocean heat flux in the eastern marginal ice zones, termed Atlantification, is not only responsible for sea ice thinning in and around the Laptev Sea, but also that the induced thickness anomalies persist beyond the Russian shelves and are potentially still measurable at the end of the Transpolar Drift after more than a year. With a tendency towards an even faster Transpolar Drift, winter sea ice growth will have less time to compensate the impact of Atlantification on sea ice growth in the eastern marginal ice zone, which will increasingly be felt in other parts of the sea ice covered Arctic.

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Suppression of Arctic sea ice growth by winter clouds and snowfall

10.21203/rs.3.rs-84779/v1 ◽

2021 ◽

Author(s):

Won-il Lim ◽

Hyo-Seok Park ◽

Andrew Stewart ◽

Kyong-Hwan Seo

Keyword(s):

Sea Ice ◽

Longwave Radiation ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Ice Growth ◽

Downward Longwave Radiation ◽

Arctic Sea ◽

The Impact

Abstract The ongoing Arctic warming has been pronounced in winter and has been associated with an increase in downward longwave radiation. While previous studies have demonstrated that poleward moisture flux into the Arctic strengthens downward longwave radiation, less attention has been given to the impact of the accompanying increase in snowfall. Here, utilizing state-of-the art sea ice models, we show that typical winter snowfall anomalies of 1.0 cm, accompanied by positive downward longwave radiation anomalies of ~5 W m-2 can decrease sea ice thickness by around 5 cm in the following spring over the Eurasian Seas. This basin-wide ice thinning is followed by a shrinking of summer ice extent in extreme cases. In the winter of 2016–17, anomalously strong warm/moist air transport combined with ~2.5 cm increase in snowfall decreased spring ice thickness by ~10 cm and decreased the following summer sea ice extent by 5–30%. Projected future reductions in the thickness of Arctic sea ice and snow will amplify the impact of anomalous winter snowfall events on winter sea ice growth and seasonal sea ice thickness.

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Evaluation of a multilayer snow scheme in NEMO-LIM3

10.5194/egusphere-egu2020-9731 ◽

2020 ◽

Author(s):

Gaëlle Gilson ◽

Thierry Fichefet ◽

Olivier Lecomte ◽

Pierre-Yves Barriat ◽

Jean Sterlin ◽

...

Keyword(s):

Sea Ice ◽

Ocean Circulation ◽

Climate Models ◽

Thickness Distribution ◽

Arctic Sea Ice ◽

The Arctic ◽

Optimum Number ◽

Ice Growth ◽

Arctic Sea ◽

The Impact

<p>Arctic sea ice is a major component of the Earth&#8217;s climate system and has been experiencing a drastic decline over the past decades, with important consequences regionally and globally. With the sustained warming of the Arctic, sea ice loss is expected to continue in the future. However, the estimation of its magnitude is model-dependent. As a result, the representation of sea ice in climate models requires further consideration. A major issue relates to the long-standing misrepresentation of snow properties on sea ice. However, the presence of snow strongly impacts sea ice growth and surface energy balance. Through its high albedo, snow reflects more solar radiation than bare sea ice does. When a snow cover is present, sea ice growth is reduced because snow is an effective insulator, with a thermal conductivity an order of magnitude lower than that of sea ice. Ocean circulation models usually use multiple layers to resolve sea ice thermodynamics but only one single layer for snow. Lecomte et al. (2013) developed a multilayer snow scheme for ocean circulation models and improved the snow depth distribution by considering the macroscopic effects of wind packing and redeposition. Since then, this snow scheme has been revisited and implemented in a more recent and much more robust NEMO-LIM version, using a simpler technical approach. In addition, new instrumental observations of snow thickness, distribution and density are available since these exploratory works. They are used in the current study to: 1) evaluate the performance of the multilayer snow scheme for sea ice in the NEMO-LIM3 model, and 2) investigate the climatic importance of this snow scheme. Here, we present results of simulations with a varying number of snow layers. By comparing these to the latest observational datasets, we recommend an optimum number of snow &#160;layers to be used in ocean circulation models in both hemispheres. Finally, we explore the impact of a few specific parameterizations of snow thermophysical properties on the representation of sea ice in climate models.</p>

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Summer Arctic sea ice albedo in CMIP5 models

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-1987-2014 ◽

2014 ◽

Vol 14 (4) ◽

pp. 1987-1998 ◽

Cited By ~ 30

Author(s):

T. Koenigk ◽

A. Devasthale ◽

K.-G. Karlsson

Keyword(s):

Sea Ice ◽

Large Scale ◽

High Surface ◽

Arctic Sea Ice ◽

Satellite Observations ◽

The Arctic ◽

Cmip5 Models ◽

Cold Temperatures ◽

Ice Conditions ◽

The Impact

Abstract. Spatial and temporal variations of summer sea ice albedo over the Arctic are analyzed using an ensemble of historical CMIP5 model simulations. The results are compared to the CLARA-SAL product that is based on long-term satellite observations. The summer sea ice albedo varies substantially among CMIP5 models, and many models show large biases compared to the CLARA-SAL product. Single summer months show an extreme spread of ice albedo among models; July values vary between 0.3 and 0.7 for individual models. The CMIP5 ensemble mean, however, agrees relatively well in the central Arctic but shows too high ice albedo near the ice edges and coasts. In most models, the ice albedo is spatially too uniformly distributed. The summer-to-summer variations seem to be underestimated in many global models, and almost no model is able to reproduce the temporal evolution of ice albedo throughout the summer fully. While the satellite observations indicate the lowest ice albedos during August, the models show minimum values in July and substantially higher values in August. Instead, the June values are often lower in the models than in the satellite observations. This is probably due to too high surface temperatures in June, leading to an early start of the melt season and too cold temperatures in August causing an earlier refreezing in the models. The summer sea ice albedo in the CMIP5 models is strongly governed by surface temperature and snow conditions, particularly during the period of melt onset in early summer and refreezing in late summer. The summer surface net solar radiation of the ice-covered Arctic areas is highly related to the ice albedo in the CMIP5 models. However, the impact of the ice albedo on the sea ice conditions in the CMIP5 models is not clearly visible. This indicates the importance of other Arctic and large-scale processes for the sea ice conditions.

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Arctic-Mid-Latitude Linkages in a Nonlinear Quasi-Geostrophic Atmospheric Model

Advances in Meteorology ◽

10.1155/2017/2691368 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Dörthe Handorf ◽

Klaus Dethloff ◽

Sabine Erxleben ◽

Ralf Jaiser ◽

Michael V. Kurgansky

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

Large Scale ◽

Atmospheric Model ◽

Reanalysis Data ◽

Arctic Sea Ice ◽

The Arctic ◽

Northern Eurasia ◽

The Arctic Oscillation ◽

The Impact

A quasi-geostrophic three-level T63 model of the wintertime atmospheric circulation of the Northern Hemisphere has been applied to investigate the impact of Arctic amplification (increase in surface air temperatures and loss of Arctic sea ice during the last 15 years) on the mid-latitude large-scale atmospheric circulation. The model demonstrates a mid-latitude response to an Arctic diabatic heating anomaly. A clear shift towards a negative phase of the Arctic Oscillation (AO−) during low sea-ice-cover conditions occurs, connected with weakening of mid-latitude westerlies over the Atlantic and colder winters over Northern Eurasia. Compared to reanalysis data, there is no clear model response with respect to the Pacific Ocean and North America.

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Impact of refreezing melt ponds on Arctic sea ice basal growth

10.5194/tc-2016-118 ◽

2016 ◽

Author(s):

Daniela Flocco ◽

Daniel L. Feltham ◽

David Schroeder ◽

Michel Tsamados

Keyword(s):

Sea Ice ◽

Climate Model ◽

Pond Water ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Growth ◽

Melt Pond ◽

Melt Ponds ◽

Ocean Properties ◽

The Impact

Abstract. Melt ponds forming over the sea ice cover in the Arctic profoundly impact the surface albedo inducing a positive feedback leading to further melting. Here we examine the processes involved in melt pond refreezing and their impact on basal sea ice growth. When ponds freeze, the ice that forms on them insulates the pond trapping it between the sea ice and the ice lid. Trapped melt ponds delay basal sea ice growth in Autumn: ice thickens only after (1) the pond water has been fully frozen and (2) a temperature gradient is established that will conduct heat away from the ocean. Sea ice thickening in the areas where ponds are present is mainly due to the pond's water refreezing. Pan-Arctic simulations with a stand-alone sea ice model and studies with a high-resolution one-dimensional, three-layer refreezing model are used to study the impact on sea ice growth of trapped melt ponds. Basal sea ice growth may be inhibited by up to two months. We estimate an inhibited basal growth of up to 228 km3, which represents 25 % of the basal sea ice growth estimated by PIOMAS during the months of September and October. The brine not released due to the inhibited basal growth during this period could have implications for the ocean properties and circulation. The impact of trapped melt ponds has not been accounted for so far in any climate model.

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Investigating future changes in the volume budget of the Arctic sea ice in a coupled climate model

The Cryosphere ◽

10.5194/tc-12-2855-2018 ◽

2018 ◽

Vol 12 (9) ◽

pp. 2855-2868 ◽

Cited By ~ 4

Author(s):

Ann Keen ◽

Ed Blockley

Keyword(s):

Sea Ice ◽

21St Century ◽

Climate Model ◽

Ice Cover ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Growth ◽

Basal Ice ◽

Arctic Sea ◽

The Impact

Abstract. We present a method for analysing changes in the modelled volume budget of the Arctic sea ice as the ice declines during the 21st century. We apply the method to the CMIP5 global coupled model HadGEM2-ES to evaluate how the budget components evolve under a range of different forcing scenarios. As the climate warms and the ice cover declines, the sea ice processes that change the most in HadGEM2-ES are summer melting at the top surface of the ice due to increased net downward radiation and basal melting due to extra heat from the warming ocean. There is also extra basal ice formation due to the thinning ice. However, the impact of these changes on the volume budget is affected by the declining ice cover. For example, as the autumn ice cover declines the volume of ice formed by basal growth declines as there is a reduced area over which this ice growth can occur. As a result, the biggest contribution to Arctic ice decline in HadGEM2-ES is the reduction in the total amount of basal ice growth during the autumn and early winter. Changes in the volume budget during the 21st century have a distinctive seasonal cycle, with processes contributing to ice decline occurring in May–June and September to November. During July and August the total amount of sea ice melt decreases, again due to the reducing ice cover. The choice of forcing scenario affects the rate of ice decline and the timing and magnitude of changes in the volume budget components. For the HadGEM2-ES model and for the range of scenarios considered for CMIP5, the mean changes in the volume budget depend strongly on the evolving ice area and are independent of the speed at which the ice cover declines.

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Decline of the Arctic 'ice factories' delayed by negative feedbacks

10.5194/egusphere-egu21-10387 ◽

2021 ◽

Author(s):

Sam Cornish ◽

Helen Johnson ◽

Alice Richards ◽

Yavor Kostov ◽

Jakob Dörr

Keyword(s):

Growth Rate ◽

Sea Ice ◽

Climate Model ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Growth ◽

Air Temperatures ◽

Arctic Sea ◽

Negative Feedbacks ◽

Ice Pack

<p>Over the past few decades, Arctic sea ice volume has been decreasing faster in summer than winter; winter sea ice growth has been increasing, helping to restore the ice pack, despite the fact that Arctic warming is most intense in the winter. This raises the questions: why? And for how long can we expect winter ice growth to keep increasing? We pose these questions with a regional focus on the Kara and Laptev seas. These seas are often termed the ice factories of the Arctic because of their outsized contributions to the Arctic sea ice budget, a consequence of their divergent settings. Using the CESM climate model ensemble, we separate out the influence of different levers on ice factory productivity (the ice growth rate), and show that 20th Century and RCP8.5 changes can be skilfully reconstructed by a linear model incorporating 2 m temperature, snow thickness, September sea ice area, total (gross) divergence and ice export. Ocean temperatures, meanwhile, help to explain the timing of the onset of freezing. Increasing air temperatures naturally decrease the growth rate, while positive contributions to growth rate are made by a decreasing September sea ice area, increasing divergence and increasing export. These positive influences are all associated with a thinning, more mobile ice pack: they are negative feedbacks on sea ice loss. In CESM, once the September sea ice area in the Kara-Laptev seas approaches zero, the year-on-year productivity of the ice factories starts to decline. We place these results in the context of observations and discuss the prospects for the productivity of the Arctic Ocean&#8217;s ice factories.</p>

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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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