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Experiments by Invited Researchers

 

Arctic Sea Ice Dynamics Using Experiments and Multi-scale Modelling

Project acronym: HyIII-HSVA-06
Name of Group Leader: Prof. Peter Sammonds, University College of London
User-Project Title: Arctic Sea Ice Dynamics Using Experiments and Multi-scale Modelling
Facility: ARCTECLAB
Proceedings TA Project: Sea ice friction and arctic sea ice dynamics
Data Management Report: There is no Data Management Report available for this project

User-Project Objectives

Summary:

Satellite and submarine observations reveal the Arctic sea ice cover is thinning at a rapid rate. Recent modelling studies show that predictions of sea ice flux into the Greenland Sea, where it may affect the strength of the North Atlantic overturning circulation, are highly sensitive to the treatment of sea ice stresses. The model representation of sea ice stresses is uncertain, but the stresses are principally determined by vertical deformation to form pressure ridges and in-plane, i.e. horizontal, deformation in the form of frictional sliding of sea ice floes past each other. Previous experimental studies and most modelling work has focussed on the role of vertical deformation in determining ice stresses but satellite observations, derived using algorithms for feature tracking, show that almost all the deformation of sea ice is due to in-plane frictional sliding. The proposed research will combine ice tank measurements of the in-plane deformation of an artificial sea ice cover with numerical simulations to give a validated model of sea ice deformation and sea ice stress. The derived model of sea ice stress will be incorporated into a Global Climate Model (GCM) sea ice model component and its predictions compared with observations of Arctic sea ice motion, extent, concentration, and thickness.

The research outputs will be used in the UCL Centre for Polar Ocean Modelling (CPOM) to generate improved predictions of sea ice mass and flux and the proposal therefore represents value for money. The new sea ice rheology module will be made available to the Hadley Centre and other modelling groups. The proposed programme of research is therefore timely in both its purely scientific and technical modelling aspects.

Our experiments carried out in July 2008 in the Arctic Environmental Test Basin at the Hamburg Ship Model Basin (HSVA) covered a wide range of issues relating to polar sea ice. In particular, we have obtained new experimental evidence relating to:

  • In-plane deformation within granular ice flows: we have investigated the relative importance of inplane and out-of-plane deformation in granular flows for a wide range of granule shapes, channel shapes, and ice thicknesses.
  • Ice-ice friction: we have undertaken a number of experiments to determine the rate and state dependence of ice-ice friction, which is a key to understanding the likelihood of in-plane deformation.
  • Rafting and consolidation: new experiments were conducted to determine the rate of consolidation of multiply rafted ice, and the strength of this consolidated ice in comparison to level ice.

Papers have been submitted for peer review to the organising committee of the 20th International Conference on Port and Ocean Engineering under Arctic Conditions 2009, June 9-12, 2009 in Luleå, Sweden and the American Geophysical Union, Fall Meeting 2008, abstract #U13C-0062

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