Modelling the sea ice in the Nares Strait

Rasmussen, Tue Kruse; Kliem, Nicolai; Kaas, Eigil

doi:10.1016/j.ocemod.2010.07.003

Cited by 18 publications

(69 citation statements)

References 31 publications

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“…For example, Rasmussen et al (2010) show an increasing trend in the volume flux through Nares Strait for 2007 and 2008. They speculate that this increase in volume flux might be one of the reasons for the lack of formation of an ice arch in those winters.…”

Section: Discussionmentioning

confidence: 98%

Geostrophic ocean currents and freshwater fluxes across the Canadian polar shelf via Nares Strait

Rabe¹,

Johnson²,

Münchow³

et al. 2012

J Mar Res

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This study discusses geostrophic ocean currents and fluxes through Nares Strait, one of the major straits connecting the Arctic Ocean to the North Atlantic across the Canadian polar shelf. Between 2003 and 2006, instruments were installed on subsea moorings to measure conductivity, temperature, pressure and velocity at high temporal and spatial resolution across the 400-m-deep strait.Here we present estimates of the variable volume and liquid freshwater fluxes, derived by geostrophic calculation, through the fraction of the cross section measured by the array. The array of conductivity-temperature recorders spanned 30 km of a 38-km-wide section between 30-and 200-m depth. This domain is 48% of the total cross-sectional area, and 74% of the cross-sectional area above 200-m depth. We demonstrate the importance of the seasonal alternation between land-fast and mobile-ice conditions, which has a strong influence on the structure of the geostrophic flow and the fluxes carried by it.The three-year mean geostrophic freshwater flux through the measured domain was 20 ± 3 mSv (relative to 34.8 psu) and no less than 28 mSv if extrapolated to the surface. No significant trend over three years was detected, but the flux of freshwater through the measured domain was about 20% larger when ice was moving than when it was land-fast, with a maximum difference between individual ice seasons of 40%. Geostrophic freshwater flux in Nares Strait was forced by both wind and alongchannel pressure difference during mobile-ice periods, and by along-channel pressure difference only under land-fast ice. Local winds and along-channel pressure differences explained 80% of the flux variance.Geostrophic volume flux through the measured domain was less strongly influenced by the state of the ice; its three-year mean was 0.47 ± 0.05 Sv, with a statistically significant increase of 15 ± 4% over this time. Geostrophic velocity was highly variable in space and time. The flow structure changed from a pattern with a surface jet in the center of the channel during mobile-ice conditions to another with a subsurface maximum in velocity adjacent to Ellesmere Island during fast-ice conditions. Over the three years, a second jet developed adjacent to the Ellesmere coast during mobile-ice regimes. Strong freshwater incursions synchronous with strong wind events were observed during mobile-ice seasons in the western half of the strait.

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Section: Discussionmentioning

confidence: 98%

Geostrophic ocean currents and freshwater fluxes across the Canadian polar shelf via Nares Strait

Rabe¹,

Johnson²,

Münchow³

et al. 2012

J Mar Res

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“…2, stress state 3), which increases its cohesive strength. Rasmussen et al (2010) performed numerical simulations of the sea ice www.the-cryosphere.net/11/2033/2017/ The Cryosphere, 11,2017 dynamics in Nares Strait and the North Water Polynya using the dynamic-thermodynamic CICE sea ice model, based on the EVP rheology. The authors noted a lack of stability and shorter lifespan of the simulated ice bridges, leading to a slower opening and lower extent of the North Water Polynya and to an earlier draining of Nares Strait compared to estimates from satellite imagery.…”

Section: Ice Bridgesmentioning

confidence: 99%

“…Hence such experiments constitute an interesting test case of their mechanical behaviour. Moreover, while other rheological models have been shown to simulate both the occurrence of ice bridges and flow stoppage, it is not at all clear whether these models, even with a fine spatial resolution (e.g., 4 km in the Lincoln Sea, about 7 km at the constriction between Kane Basin and Smith Sound and 10 km in Baffin Bay in the model of Rasmussen et al, 2010, and about 3 by 4 km in the realistic simulations of Nares Strait of Dumont et al, 2009), are also able to account for the presence of multiple arch-like leads within and upstream of the channel, as observed from satellite imagery (e.g., see Fig. 1b).…”

Section: Ice Bridgesmentioning

confidence: 99%

Ice bridges and ridges in the Maxwell-EB sea ice rheology

et al. 2017

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Abstract. This paper presents a first implementation of a new rheological model for sea ice on geophysical scales. This continuum model, called Maxwell elasto-brittle (Maxwell-EB), is based on a Maxwell constitutive law, a progressive damage mechanism that is coupled to both the elastic modulus and apparent viscosity of the ice cover and a MohrCoulomb damage criterion that allows for pure (uniaxial and biaxial) tensile strength. The model is tested on the basis of its capability to reproduce the complex mechanical and dynamical behaviour of sea ice drifting through a narrow passage. Idealized as well as realistic simulations of the flow of ice through Nares Strait are presented. These demonstrate that the model reproduces the formation of stable ice bridges as well as the stoppage of the flow, a phenomenon occurring within numerous channels of the Arctic. In agreement with observations, the model captures the propagation of damage along narrow arch-like kinematic features, the discontinuities in the velocity field across these features dividing the ice cover into floes, the strong spatial localization of the thickest, ridged ice, the presence of landfast ice in bays and fjords and the opening of polynyas downstream of the strait. The model represents various dynamical behaviours linked to an overall weakening of the ice cover and to the shorter lifespan of ice bridges, with implications in terms of increased ice export through narrow outflow pathways of the Arctic.

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“…Both Sou and Flato (2009) and Terwisscha van Scheltinga et al (2010) attributed the much-lowerthan-observation ice flux through Nares Strait to wind forcing, which does not have enough resolution to resolve the along-strait winds. With a high-resolution wind forcing, Rasmussen et al (2010) were able to reproduce much more reasonable ice flux through this narrow channel.…”

Section: Baffin Baymentioning

confidence: 99%

Thermodynamic and dynamic ice thickness contributions in the Canadian Arctic Archipelago in NEMO-LIM2 numerical simulations

Sun

Chan

et al. 2018

The Cryosphere

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Abstract. Sea ice thickness evolution within the Canadian Arctic Archipelago (CAA) is of great interest to science, as well as local communities and their economy. In this study, based on the NEMO numerical framework including the LIM2 sea ice module, simulations at both 1/4 and 1/12 • horizontal resolution were conducted from 2002 to 2016. The model captures well the general spatial distribution of ice thickness in the CAA region, with very thick sea ice (∼ 4 m and thicker) in the northern CAA, thick sea ice (2.5 to 3 m) in the west-central Parry Channel and M'Clintock Channel, and thin (< 2 m) ice (in winter months) on the east side of CAA (e.g., eastern Parry Channel, Baffin Island coast) and in the channels in southern areas. Even though the configurations still have resolution limitations in resolving the exact observation sites, simulated ice thickness compares reasonably (seasonal cycle and amplitudes) with weekly Environment and Climate Change Canada (ECCC) New Ice Thickness Program data at first-year landfast ice sites except at the northern sites with high concentration of old ice. At 1/4 to 1/12 • scale, model resolution does not play a significant role in the sea ice simulation except to improve local dynamics because of better coastline representation. Sea ice growth is decomposed into thermodynamic and dynamic (including all non-thermodynamic processes in the model) contributions to study the ice thickness evolution. Relatively smaller thermodynamic contribution to ice growth between December and the following April is found in the thick and very thick ice regions, with larger contributions in the thin ice-covered region. No significant trend in winter maximum ice volume is found in the northern CAA and Baffin Bay while a decline (r 2 ≈ 0.6, p < 0.01) is simulated in Parry Channel region. The two main contributors (thermodynamic growth and lateral transport) have high interannual variabilities which largely balance each other, so that maximum ice volume can vary interannually by ±12 % in the northern CAA, ±15 % in Parry Channel, and ±9 % in Baffin Bay. Further quantitative evaluation is required.

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Modelling the sea ice in the Nares Strait

Cited by 18 publications

References 31 publications

Geostrophic ocean currents and freshwater fluxes across the Canadian polar shelf via Nares Strait

Geostrophic ocean currents and freshwater fluxes across the Canadian polar shelf via Nares Strait

Ice bridges and ridges in the Maxwell-EB sea ice rheology

Thermodynamic and dynamic ice thickness contributions in the Canadian Arctic Archipelago in NEMO-LIM2 numerical simulations

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