Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean

Graham, Robert M.; Itkin, Polona; Meyer, Amélie; Sundfjord, Arild; Spreen, Gunnar; Smedsrud, Lars H.; Liston, Glen E.; Cheng, Bin; Cohen, Lior; Divine, Dmitry; Fer, Ilker; Fransson, Agneta; Gerland, Sebastian; Haapala, Jari; Hudson, Stephen R.; Johansson, A. Malin; King, Jennifer; Merkouriadi, Ioanna; Peterson, Algot Kristoffer; Provost, Christine; Randelhoff, Achim; Rinke, Annette; Rösel, Anja; Sennéchael, Nathalie; Walden, Von P.; Duarte, Pedro; Assmy, Philipp; Steen, Harald B.; Granskog, Mats A.

doi:10.1038/s41598-019-45574-5

Cited by 80 publications

(130 citation statements)

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“…During our survey, the wind variability was weak and no evidence of inertial motions were seen. However, storms are strong and frequent in the Arctic and are observed to lead to energetic turbulence and increased heat fluxes (Graham et al, ; Meyer, Fer, et al, ). The possible contribution of FSI was not addressed in these studies, or in the Arctic fronts in general.…”

Section: Discussionmentioning

confidence: 99%

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Observations of Turbulence at a Near‐Surface Temperature Front in the Arctic Ocean

et al. 2020

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High-resolution ocean temperature, salinity, current, and turbulence data were collected at an Arctic thermohaline front in the Nansen Basin. The front was close to the sea ice edge and separated the cold and fresh surface melt water from the warm and saline mixed layer. Measurements were made on 18 September 2018, in the upper 100 m, from a research vessel and an autonomous underwater vehicle. Destabilizing surface buoyancy fluxes from a combination of heat loss to the atmosphere and cross-front Ekman transport by down-front winds reduced the potential vorticity in the upper ocean. Turbulence structure in the mixed layer was generally consistent with turbulence production through convection by heat loss to atmosphere and mechanical forcing by moderate winds. Conditions at the front were favorable for forced symmetric instability, a mechanism drawing energy from the frontal geostrophic current. A clear signature of increased dissipation from symmetric instability could not be identified; however, this instability could potentially account for the increased dissipation rates at the front location down to 40 m depth that could not be explained by the atmospheric forcing. This turbulence was associated with turbulent heat fluxes of up to 10 W m −2 , eroding the warm and cold intrusions observed between 30 and 60 m depth. A Seaglider sampled across a similar frontal structure in the same region 10 days after our survey. The submesoscale-to-turbulence-scale transitions and resulting mixing can be widespread and important in the Atlantic sector of the Arctic Ocean. Plain Language SummaryOn 18 September 2018, high-resolution temperature, salinity, current, and turbulence data were collected near a surface temperature and salinity front in the Nansen Basin north of Svalbard, within the framework of the Nansen Legacy Project. Measurements were performed from the research icebreaker Kronprins Haakon and using an autonomous underwater vehicle. The front separates warm and salty Atlantic-origin waters from cold and fresh Arctic-origin waters. Energetic turbulence in the upper 30 m was consistent with convection by heat loss to the atmosphere and mechanical forcing by moderate winds at the surface of the ocean. At the front, the conditions were favorable for forced symmetric instability, a mechanism drawing energy from the large-scale current. The contribution to turbulence from this instability could not be clearly identified but can be potentially important. Such observations linking 1-3 km scales to turbulence in the Arctic Ocean are rare. Turbulence at a front in the Arctic has consequences on the heat and nutrient transport from the slope to the deep Arctic Basin. A Seaglider sampled across a similar frontal structure in the same region end of September 2018. Observed frontal structure and mixing processes can be common in the Atlantic sector of the Arctic Ocean.

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Section: Discussionmentioning

confidence: 99%

“…Near 89°N, increased dissipation rates have been recorded in the pycnocline following strong winds, coherent with energized near‐inertial internal waves (Fer, ). North of Svalbard, winter storms increased the pycnocline fluxes by a factor of 2 (Meyer, Fer, et al, ) and the ocean‐to‐ice fluxes by a factor of 3 (Graham et al, ).…”

Section: Introductionmentioning

confidence: 99%

Observations of Turbulence at a Near‐Surface Temperature Front in the Arctic Ocean

et al. 2020

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“…Cyclones are just one of several phenomena that give rise to sea ice variability in the Barents Sea. The impact of cyclones on sea ice depends on their characteristics and spans from surface warming to mechanical ice breakup (Graham et al, 2019). Other factors influencing wintertime sea ice variability are the inflow of warm Atlantic water into the Barents Sea driven by local wind forcing (e.g., Akperov et al, 2020; Alexeev et al, 2017; Årthun et al, 2012; Smedsrud et al, 2013), as well as the preconditions at the end of the melting season.…”

Section: Discussionmentioning

confidence: 99%

Control of Barents Sea Wintertime Cyclone Variability by Large‐Scale Atmospheric Flow

Madonna

Hes

et al. 2020

Geophysical Research Letters

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Extratropical cyclones transport heat and moisture into the Arctic, which can promote surface warming and sea ice melt. We investigate wintertime cyclone variability in the Barents Sea region to understand what controls the impacts, frequency, and path of cyclones at high latitudes. Large-scale atmospheric conditions are found to be key, with the strongest surface warming from cyclones originating south of 60 • N in the North Atlantic and steered northeastward by the upper-level flow. Atmospheric conditions also control cyclone variability in the Barents proper: Months with many cyclones are characterized by an absence of high-latitude blocking and enhanced local baroclinicity, due to the presence of strong upper-level winds and a southwest-northeast tilted jet stream more than changes in sea ice. This study confirms that Arctic cyclones exhibit large interannual variability, and accounting for this variability reveals that trends in Barents cyclone frequency are not robust over the 1979-2018 period. Plain Language Summary Extratropical cyclones traveling from the midlatitudes can cause surface warming and sea ice melt upon reaching the Arctic. Focusing on the North Atlantic, this study aims to better understand what controls the number of cyclones reaching the Barents Sea, the differences in their climate impacts, and the exact paths they take on their journey northward. We find that cyclones originating south of 60 • N produce the strongest Arctic warming. The large-scale atmospheric flow is key for steering the cyclones: more cyclones are found in the Barents Sea when the North Atlantic jet stream exhibits a pronounced southwest-northeast tilt, while fewer cyclones are found when quasi-stationary high-pressure systems, referred to as "blocking" systems, form at high latitudes. No remarkable differences in sea ice conditions seem to characterize periods with many/few cyclones in the Barents Sea. The winter-to-winter variability in the number of Arctic cyclones is large, and no robust trends are observed over the last 40 years.

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“…During our survey, the wind variability was weak and no evidence of inertial motions were seen. However, storms are strong and frequent in the Arctic and are observed to lead to energetic turbulence and increased heat fluxes (Graham et al, 2019;. The possible contribution of FSI was not addressed in these studies, or in the Arctic fronts in general.…”

Section: Comparison With Other Frontsmentioning

confidence: 95%

“…Near 89 • N, increased dissipation rates have been recorded in the pycnocline following strong winds, coherent with energized near-inertial internal waves (Fer, 2014). North of Svalbard, winter storms increased the pycnocline fluxes by a factor of 2 and the ocean-to-ice fluxes by a factor of 3 (Graham et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Observations of turbulence at a near-surface temperature front in the Arctic Ocean

Koenig

Fer

Kolås

et al. 2020

Preprint

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Measurements made at an Arctic thermohaline front show turbulence production through convection and forced symmetric instability, a mechanism drawing energy from the frontal geostrophic current. Destabilizing surface buoyancy fluxes from a combination of heat loss to the atmosphere and cross-front Ekman transport by down-front winds reduce the potential vorticity in the upper ocean. The front, located in the Nansen Basin close to the sea ice edge, separates the cold and fresh surface melt water from the warm and saline mixed layer. High resolution temperature, salinity, current and turbulence data were collected in the upper 100 m, on 18 September 2018 across the front from a research vessel and an autonomous underwater vehicle. The AUV was deployed to autonomously collect high resolution data across the front using adaptive sampling. Both front detection and sampling location were decided by a state-based autonomous agent running onboard the AUV, optimizing data collection across and along the front.In addition to convection by heat loss to atmosphere and mechanical forcing by moderate wind in the mixed layer, forced symmetric instability contributed with comparable magnitude in generation of turbulence at the front location down to 40 m depth. This turbulence was associated with turbulent heat fluxes of up to 10 W.m-2, eroding the warm and cold intrusions observed at respectively 35 and 55 m depth. A similar frontal structure has been crossed by a Seaglider in the same region 10 days after our survey. The submesoscale-to-turbulence scale transitions and resulting mixing can be widespread and important in the Atlantic sector of the Arctic Ocean.

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Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean

Cited by 80 publications

References 99 publications

Observations of Turbulence at a Near‐Surface Temperature Front in the Arctic Ocean

Observations of Turbulence at a Near‐Surface Temperature Front in the Arctic Ocean

Control of Barents Sea Wintertime Cyclone Variability by Large‐Scale Atmospheric Flow

Observations of turbulence at a near-surface temperature front in the Arctic Ocean

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