The Dynamic Response of Sea Ice and Ice-Ocean Models Using Different Sea-Ice Rheologies

9818711

Tremblay

Correctly modeling sea ice in global climate models is important in order to have realistic high-latitude ocean-atmosphere interactions and reasonable fluxes of salt and fresh water associated with the freezing and melting of sea ice in different locations. The dynamic component of the sea ice model is fundamental to that goal. The motion of sea ice is, in turn, strongly affected by the internal ice forces caused by interactions between different ice floes. In the past two decades, various approaches have been proposed for modeling those interactions and predicting sea ice motion. The purpose of this study is to better understand the differences in the behavior of two different sea ice models and to determine whether a different formulation of the sea ice interactions leads to significant differences in the dynamic behavior of sea ice and coupled ice-ocean models. This project will first compare the sea ice trajectories simulated by two (viscous-plastic) sea ice models, forced with the same atmospheric and oceanic fields, against the buoy drift data from the International Arctic Buoy program and satellite derived (SAR) sea ice velocities. The two models are 1- the standard viscous-plastic approach with an elliptical yield curve and a normal flow rule (Hibler79) and, 2- a granular material approach with a

Mohr-Coulomb yield curve and a double-sliding deformation law with dilatancy included (Tremblay and Mysak, 97b and Flato and Hibler92). The two sea ice models will then be coupled to the Lamont-Doherty and SCRUM three-dimensional ocean models to compare the sensitivity of the coupled models to increased radiative fluxes associated with global warming scenario. The completion of this project will lead to an improved understanding of the sensitivity of coupled ice-ocean models to the sea dynamic treatment. To get a better perspective, it will also be compared with the sensitivity of the sea-ice models to other errors, such as in the wind forcing fields.