Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-13
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
22 Feb 2016
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Sea Ice Deformation in a Coupled Ocean-Sea Ice Model and in Satellite Remote Sensing Data
Gunnar Spreen1,2, Ron Kwok1, Dimitris Menemenlis1, and An T. Nguyen1,3 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
2University of Bremen, Institute of Environmental Physics, Bremen, Germany
3now at: Massachusetts Institute of Technology, Cambridge, MA, USA
Abstract. A realistic representation of sea ice deformation in models is important for accurate simulation of the sea ice mass balance. In this study, model ice strength sensitivity experiments show an increase in Arctic Basin sea ice volume of 7 % and 35 % for a decrease in ice strength of, respectively, 30 % and 70 %, after 8 years of model integration. This volume increase is caused by a combination of dynamic and thermodynamic processes. On the one hand, a weaker ice cover initially produces more ice due to increased deformation and new ice growth. The thickening of the ice, on the other hand, increases the ice strength and decreases the sea ice volume export out of the Arctic Basin. The balance of these processes leads to a new equilibrium Arctic Basin ice volume. Simulated sea ice deformation strain rates from model simulations with 4.5, 9, and 18-km horizontal grid spacing are compared with synthetic aperture radar satellite observations (RGPS). All three model simulations can reproduce the large-scale ice deformation patterns but they do not reproduce all aspects of the observed deformation rates. The overall sea ice deformation rate is about 50 % lower in all model solutions than in the satellite observations, especially in the seasonal sea ice zone. Small scale sea ice deformation and linear kinematic features are not adequately reproduced. A decrease in model grid spacing, however, produces a higher density and more localized ice deformation features. Overall, the 4.5-km simulation produces the lowest misfits in divergence, vorticity, and shear when compared with RGPS data. Not addressed in this study is whether the differences between simulated and observed deformation rates are an intrinsic limitation of the viscous-plastic sea ice rheology that was used in the sensitivity experiments, or whether it indicates a lack of adjustment of existing model parameters to better represent these processes. Either way, this study provides new quantitative metrics for existing and new sea ice rheologies to strive for.

Citation: Spreen, G., Kwok, R., Menemenlis, D., and Nguyen, A. T.: Sea Ice Deformation in a Coupled Ocean-Sea Ice Model and in Satellite Remote Sensing Data, The Cryosphere Discuss., doi:10.5194/tc-2016-13, in review, 2016.
Gunnar Spreen et al.
Gunnar Spreen et al.
Gunnar Spreen et al.

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