In WP2, the parameterizations in question are derived, or at least inspired, by the analysis of the behavior of simulated granular materials. They are inserted in a rheological model of an elasto-visco-brittle type. The work of the candidate will consist in (i) implementing these new parameterizations in an existing large-scale coupled sea ice-ocean model, NeXtSIM, with the help of a research engineer (ii) validating the new parameterizations on the basis of comparisons with observations of ice deformation and drift (iii) adjusting, if necessary, the mechanical parameterizations according to the results of these comparisons and in the view of the specific needs of regional and global scales sea ice models.
The deliverable of the planned work is a rheological model for sea ice, which is an improved version of the existing viscous-elasto-brittle models and which is rigorously tested on the basis of observations.
The candidate will have active interactions with a team of researchers, PhD students, post-docs and engineers, in particular the participants of the SASIP project distributed between the Institut des Sciences de la Terre (ISTerre) and the Institut des Géosciences de l'Environnement (IGE) in Grenoble (France) and the Nansen Environmental and Remote Sensing Center in Bergen (Norway). He will be supervised primarily by Véronique Dansereau (ISTerre), Jérôme Weiss (ISTerre) and Pierre Rampal (IGE).

The desired start date is the beginning of June 2023, if not, the beginning of September 2023.

Sea ice - the thin layer of ice that covers the polar oceans - is a complex geophysical object that is constantly fracturing under the influence of the winds and ocean currents. In winter and in the central Arctic, it behaves as a quasi-continuous and damageable solid, while in the melt season and especially in the marginal Arctic seas, it appears as an aggregate of ice plates (called floes) whose mechanical behavior at low concentration is dominated by collisions and friction between the floes. Capturing the mechanical transitions (spatial and temporal) between these two states in continuous models of sea ice used for operational and climate prediction purposes is essential to adequately represent the rapid and long-term variations in its extent and thickness.
This is the goal of work package 2 (WP2)of the the SASIP project (the Scale Aware Sea Ice Project, https://sasip-climate.github.io)
In this context, one of the main tasks of WP2 is to develop, implement and test mechanical parameterizations for continuous sea ice models that reflect the dependence of its large-scale (10-100 km) mechanical strength on its concentration, degree of fracturing and floe size distribution at small scales (< 10 km).

ISTerre is a Joint Research Unit of Grenoble Alpes University, CNRS, USMB, IRD and Gustave Eiffel University, located 1381 rue de la Piscine 38400 Saint-Martin d'Hères and on the Scientific Campus of Le Bourget du Lac. It is part of the Observatoire des Sciences de l'Univers de Grenoble (OSUG) and of the PAGE Research Pole of the University Grenoble Alpes (UGA). It employs around 300 people for an average annual budget of 7 M€. It is organized around 9 research and service teams, the scientific objective being the physical and chemical study of planet Earth, with a particular focus on coupling between observations of natural objects, experimentation and modeling of the associated complex processes. ISTerre also carries out solid Earth observation missions, hosts and maintains national geophysical instrument parks and a data centre.