Preprints
https://doi.org/10.5194/egusphere-2022-1481
https://doi.org/10.5194/egusphere-2022-1481
 
23 Dec 2022
23 Dec 2022
Status: this preprint is open for discussion.

Deformation lines in Arctic sea ice: intersection angles distribution and mechanical properties

Damien Ringeisen1,2,3,, Nils Hutter4,1,, and Luisa von Albedyll1 Damien Ringeisen et al.
  • 1Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
  • 2MARUM – Center for Marine Environmental Sciences, Leobener Str. 8, 28359, Bremen, Germany
  • 3Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, QC, Canada
  • 4Cooperative Institute for Climate, Ocean, and Ecosystem Studies (CICOES), University of Washington, Seattle, WA, United States
  • These authors contributed equally to this work.

Abstract. In Arctic sea ice, the intersection angles between Linear Kinematic Features (LKFs) are linked to the internal mechanical properties. Sea ice rheological models struggle to reproduce the intersection angles between LKFs in Arctic sea ice. We aim to obtain an intersection angle distribution (IAD) from observational data to serve as a reference for high-resolution sea ice models and to infer the mechanical properties of the sea ice cover. We use the sea ice vorticity to discriminate between acute and obtuse LKFs intersection angles within two sea ice deformation datasets: the RGPS and a new dataset from the MOSAiC drift experiment. Acute angles dominate the IAD, with single peaks at 48º ± 2 and 45º ± 7. The IAD agrees well between both datasets, despite the difference in scale, time periods, and geographical location. The divergence and shear rates of the LKFs also have the same distribution. The dilatancy angle (the ratio of shear and divergence) is not correlated with the intersection angle. Using the IAD, we infer an internal angle of friction in sea ice of µI= 0.66 ± 0.02 and µI= 0.75 ± 0.05. The shape of the yield curve or the plastic potential derived from the observed IAD resembles the teardrop or a Mohr–Coulomb shape. With those new insights, sea ice rheologies used in models can be adapted or re-designed to improve the representation of sea-ice dynamics.

Damien Ringeisen et al.

Status: open (until 17 Feb 2023)

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Damien Ringeisen et al.

Data sets

Linear Kinematic Features (leads & pressure ridges) detected and tracked in RADARSAT Geophys- ical Processor System (RGPS) sea-ice deformation data from 1997 to 2008 Hutter, N., Zampieri, L., and Losch, M. https://doi.org/10.1594/PANGAEA.898114

Model code and software

lkf_tools: a code to detect and track Linear Kinematic Features (LKFs) in sea-ice deformation data (Version v1.0) Hutter, N. https://doi.org/10.5281/zenodo.2560078

Damien Ringeisen et al.

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Short summary
When sea ice is put into motion by wind and ocean currents, it deforms following narrow lines. Our two datasets at different places and resolutions show that the intersection angle between these lines is often acute and rarely obtuse. We use the orientation of narrow lines to gain indications about the mechanical properties of sea ice and to constrain how to design sea ice mechanical models for high-resolution simulation of the Arctic and improve regional predictions of sea ice motion.