Grounded sea ice and tensile strength Landfast ice formation in climate models

• Main Authors: Sterlin, Jean, Huot, Pierre-Vincent, Chevallier, Mathieu, Massonnet, François, Fichefet, Thierry
• Format: Conference Object
• Language: English
• Published: Zenodo 2019
• Subjects: Land fast ice; Sea ice model; Ocean General Circulation Model; Arctic climate; Antarc*; Antarctic; Arctic; Iceberg*; Orca; Sea ice
• Online Access: https://doi.org/10.5281/zenodo.4545536

Landfast ice is the part of sea ice fastened to the coast. As the landfast ice is immobile, its has an influence on the interactions between the ocean and the atmosphere, the fresh water budgets, deep water formations and the stability of the ice cover. It plays equally a role for coastal ecosystems in the Arctic and Antarctic. Two main mechanisms for landfast ice formation are known in the Arctic. The first occurs when the ice is thick enough to ground on the sea floor. The weight of ice unbalanced by buoyancy forces leads to basal stress limiting its displacements. Over deeper waters, landfast ice can also be sustained by tensile strength. The fast ice develops as arches anchored to islands, grounded icebergs, or other points such as the shoreline. To model the landfast ice, grounding schemes have been introduced (Rousset et al., 2013; Lemieux et al., 2015) while the yield curve of the ice have been modified to account for tensile strength (Dumont et al., 2009; Lemieux et al., 2016; Olason, 2016), showing promising results for regional modelling. However, for global models, little is known on the behaviour of the grounding schemes with ice thickness distribution and coarser bathymetries, neither the effects of tensile strength on the ice dynamics at the poles, nor the impact of landfast ice on the global climate on the decadal time scale. In this study, we use NEMO-LIM3 to test Lemieux et al. (2015) grounding scheme. We introduce isotropic tensile strength in the ice rheology. We validate the representation of fast ice and the dynamic of drift ice. We then run a simulation on global ORCA grid at 1 degree resolution, from the years 1958 to 2015. We formulate an initial assessment of the importance of landfast ice for current climate models and we suggest of set of paramaters that can be used.