Abstract
The drift and deformation of sea ice floating on the polar oceans is caused by the applied wind and ocean currents. Over ocean basin length scales the internal stresses and boundary conditions of the sea ice pack result in observable deformation patterns. Cracks and leads can be observed in satellite images and within the velocity fields generated from floe tracking. In a climate sea ice model the deformation of sea ice over ocean basin length scales is modelled using a rheology that represents the relationship between stresses and deformation within the sea ice cover. Here we investigate the link between emergent deformation characteristics and the underlying internal sea ice stresses using the Los Alamos numerical sea ice climate model. We have developed an idealized square domain, focusing on the role of sea ice rheologies in producing deformation at spatial resolutions of up to 500 m. We use the elastic anisotropic plastic (EAP) and elastic viscous plastic (EVP) rheologies, comparing their stability, with the EAP rheology producing sharper deformation features than EVP at all space and time resolutions. Sea ice within the domain is forced by idealized winds, allowing for the emergence of five distinct deformation types. Two for a low confinement ratio: convergent and expansive stresses. Two about a critical confinement ratio: isotropic and anisotropic conditions. One for a high confinement ratio and isotropic sea ice. Using the EAP rheology and through the modification of initial conditions and forcing, we show the emergence of the power law of strain rate, in accordance with observations.This article is part of the theme issue ‘Modelling of sea-ice phenomena’.
Highlights
Sea ice floating on the polar oceans is composed of many individual floes and floe aggregates
To represent floe-scale interactions within a continuum model, Wilchinsky & Feltham [3] developed the elastic anisotropic plastic (EAP) rheology that sums together the forces arising between many diamondshaped floes within an arbitrary area of sea ice cover. This rheology was implemented into the Los Alamos sea ice model CICE by Tsamados et al [14], with further investigations into its role in the sea ice force balance presented by Heorton et al [2]
A laboratory experiment where the internal stresses could be observed in comparison to imposed external stresses, if possible, would produce a distribution of stress confinement ratio that can be used to contrast with those we show for the EAP and elastic viscous plastic (EVP) rheologies in this paper
Summary
Sea ice floating on the polar oceans is composed of many individual floes and floe aggregates. To represent floe-scale interactions within a continuum model, Wilchinsky & Feltham [3] developed the EAP rheology that sums together the forces arising between many diamondshaped floes within an arbitrary area of sea ice cover. This rheology was implemented into the Los Alamos sea ice model CICE by Tsamados et al [14], with further investigations into its role in the sea ice force balance presented by Heorton et al [2]. The structure tensor changes in time due to local forcing with
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