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The evolution of a coupled ice shelf-ocean system under different climate states

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Grosfeld, K. and Sandhäger, H. (2004): The evolution of a coupled ice shelf-ocean system under different climate states , Global and planetary change, 42 , pp. 107-132 . doi: 10.1016/j.gloplacha.2003.11.004
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Abstract:

Based on a new approach for coupled applications of an ice shelf model andan ocean general circulation model, we investigate the evolution of an iceshelf - ocean system and its sensitivity to changed climatic boundary conditions.Combining established 3D models into a coupled model system enabled us tostudy the reaction and feedbacks of each component to changes at theirinterface, the ice shelf base. After calculating the dynamics for prescribed initialice shelf and bathymetric geometries, the basal mass balance determines thesystem evolution. In order to explore possible developments for given boundaryconditions, an idealized geometry has been chosen, reflecting basic featuresof the Filchner-Ronne Ice Shelf, Antarctica. The model system is found to beespecially sensitive in regions where high ablation or accretion rates occur. IceShelf Water formation as well as the build up of a marine ice body, resultingfrom accretion of marine ice, is simulated, indicating strong interaction processes.To improve consistency between modeled and observed ice shelf behavior,we incorporate the typical cycle of steady ice front advance and sudden retreatdue to tabular iceberg calving in our time-dependent simulations. Our basichypothesis is that iceberg break off is associated with abrupt crack propagationalong elongated anomalies of the inherent stress field of the ice body. This newconcept yields glaciologically plausible results and represents an auspicious basisfor the development of a thorough calving criterion.Experiments under different climatic conditions (ocean warming of 0.2 and 0.5 °Cand doubled surface accumulation rates) show the coupled model system to besensitive especially to ocean warming. Increased basal melt rates of 100 % forthe 0.5 °C ocean warming scenario and an asymmetric development of ice shelfthicknesses suggest a high vulnerability of ice shelf regions, which representpivotal areas between the Antarctic Ice Sheet and the Southern Ocean.

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