A dynamical model of Kara Sea land‐fast ice

Abstract

This paper introduces modifications to the traditional viscous‐plastic sea‐ice dynamical model, which are necessary to model land‐fast ice in the Kara Sea in a realistic manner. The most important modifications are an increase in the maximum viscosity from the standard value of ζmax=(2.5×108s)P to ζmax=(1013s)P, and to use a solver for the momentum equation capable of correctly solving for small ice velocities (the limit here is set to 10−4 m/s). Given these modifications, a necessary condition for a realistic fast‐ice simulation is that the yield curve give sufficient uniaxial compressive strength. This is consistent with the idea that land‐fast ice in the Kara Sea forms primarily via static arching. The modified model is tested and tuned using forcing data and observations from 1997 and 1998. The results show that it is possible to model land‐fast ice using this model with the modifications mentioned above. The model performs well in terms of modeled fast‐ice extent, but suffers from unrealistic break‐ups during the start and end of the fast‐ice season. The main results are that fast ice in the Kara Sea is supported by arching of the ice, the arches footers resting on a chain of islands off shore.

Using sea‐ice deformation fields to constrain the mechanical strength parameters of geophysical sea ice

“…The VP elliptical rheology parameters ( and e ) are typically adjusted such that the difference between the simulated and observed sea‐ice drift [ Hibler , ; Hibler and Walsh , ; Kreyscher et al ., ; Dansereau , ] and/or sea‐ice thickness and extent fields [ Miller et al ., ; Ungermann et al ., ] is minimum. Depending on the model configuration, spatial resolution, and forcing used, estimates of in modelling studies vary between kN m −2 and kN m −2 [ Hibler , ; Kreyscher et al ., ; Hibler and Walsh , ; Olason , ]. The standard values used by the sea‐ice modeling community are kN m −2 and e = 2 [e.g., Hibler and Walsh , ; Zhang and Hibler , ; Hunke and Dukowicz , ; Lemieux and Tremblay , ].…”

The Impact of Tides on Simulated Landfast Ice in a Pan‐Arctic Ice‐Ocean Model

“…Modeling experiments suggest that grounding is also an important mechanism for the presence of landfast ice in the East Siberian Sea (Lemieux et al, , ). As the Kara Sea is overall deeper than the East Siberian and Laptev Seas, grounding is less effective and it is thought that a series of islands act as pinning points for stabilizing its landfast ice cover (Divine et al, ; Olason, ). In the Chukchi and Beaufort Seas, where the continental shelves are narrower than in the East Siberian and Laptev Seas, the landfast ice cover can extend a few tens of kilometers away from the coast.…”

A basal stress parameterization for modeling landfast ice

“…Other studies, however, suggest that ice keels play a minor role [ Reimnitz et al ., ; Eicken et al ., ] and that river water plumes instead are the primary drivers [ Eicken et al ., ]. In the Kara Sea, a series of archipelagos contribute to the stabilization of the landfast ice cover [ Divine et al ., ; Ólason , ]. The ice arch in Nares Strait can form because the sea ice cover can resist tensile stresses [ Dumont et al ., ].…”

“…They demonstrated, in 1‐D experiments, that landfast ice can be stable over many weeks with this approach. Ólason [] was able to model landfast ice in the Kara Sea region by using a high resolution grid and by adjusting the sea ice mechanical parameters in a viscous‐plastic sea ice model. Following the work of König Beatty and Holland [], Itkin et al .…”