Geophysics seminar: Cyrille Mosbeux (IGPP) "Modeling the ice sheet using data assimilation "

05/25/2018 - 3:30pm to 4:30pm
Munk Conference Room
Event Description: 
The current global warming seems to have direct consequences on ice-sheet mass loss. Unfortunately, as highlighted in the last IPCC report, current ice-sheets models face several difficulties in assessing the future evolution of the dynamics of ice sheets for the next century. Indeed, projections are still plagued with high uncertainties partially due to the poor representation of occurring physical processes, but also due to the poor initialization of ice flow models. Indeed, some parameters, such as the basal friction between ice sheet and bedrock as well as the basal topography, are still badly known because of a lake of direct observations or large uncertainty on measurements. Improving the knowledge of these two parameters for Greenland and Antarctica is therefore a prerequisite for making reliable projections. Data assimilation and inverse methods have been developed in order to overcome this problem.

In a first part of the presentation, two different algorithms to better constrain simultaneously basal friction and bedrock elevation parameters (using more reliable surface observations) are presented. Both algorithms have been implemented in the finite element ice sheet and ice flow model Elmer/Ice and tested in a twin experiment showing a clear improvement of both parameters knowledge. The application of both algorithms to regions such as the Wilkes Land in Antarctica reduces the uncertainty on basal conditions, for instance providing more details to the bedrock geometry when compared to usual DEM. Moreover, the reconstruction of both bedrock elevation and basal friction significantly decreases ice flux divergence anomalies when compared to classical methods initialization methods. We finally study the impact of such inversion on prognostic simulation in order to compare the efficiency of the two algorithms to better constrain future ice-sheet contribution to sea level rise.

In a second part, we briefly show a piece of work consisting in the modelling of the Ross Ice Shelf (Antarctica) from regional scale (100-1000 km) to small scale (1m to 1 km) allowing a better understanding of the physical processes involved in the ice flow of the region.

For more information on this event, contact: 
Adina Pusok
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