ENAC Seminar Series by Dr. Ruzica Dadic & Dr. Guillaume Jouvet
Event details
| Date | 08.11.2018 |
| Hour | 09:30 › 11:30 |
| Speaker | Dr. Ruzica Dadic Dr. Guillaume Jouvet |
| Location | |
| Category | Conferences - Seminars |
9:30 – 10:30 – Dr. Ruzica Dadic
Senior Research Fellow, Antarctic Research Centre, VUW, NZ
From Snowflakes to Ice Sheets: why we need a multi-scale approach to understand past, present and future of the cryosphere
Ice sheets both control global sea level and provide our best records of greenhouse gases in the past. Loss of land-based ice contributes much of the uncertainty in global sea level projections for the coming century. While our current estimates of ice sheet mass balance have vastly improved with the onset of satellite observations, large uncertainties remain in our projections of ice sheet volume and its contribution to sea level. To improve those projections, we need to improve our understanding of past changes and the relationships between greenhouse gases, global temperatures, and global sea level. Ice cores provide a rich archive of past atmospheric composition and temperature but the resolution of ice core data, especially in times of rapid climate change, is currently limited by the lack of understanding of small scale processes. These processes include a) metamorphism from snow to ice, b) post-depositional changes in the isotope composition of ice and c) changes in snow/ice albedo. These processes are not only dependent on ice physics, but also on the interaction of the ice with the atmosphere. Improvements in the accuracy and precision of ice core records documenting rapid changes in greenhouse gas concentration, and the associated climate variations and environmental conditions, would be a significant advance in our understanding of past and future climate and ice sheet behaviour. Here I present recent advances in process understanding at multiple scales underlining their importance for ice sheet mass balance.
10:30 – 11:30 – Dr. Guillaume Jouvet
Senior scientist, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETHZ
Glacial motion: From first observations to state-of-the-art modelling
Glacial motion governs the advance and the retreat of glaciers. It has long been debated whether the observed surface motion is the result of ice deformation or basal sliding over the bedrock. It is now recognized that both mechanisms play an important role in glacier motion, depending on conditions at the glacier bed. In this presentation, I will first present how glacial motion is commonly modelled by using non-Newtonian fluid mechanics. This involves overcoming several numerical challenges in solving the underlying equations with complex and time-changing geometries that are characteristic of mountain glaciers. Here I will present an Eulerian method that can tackle these difficulties and simulate the time evolution of glaciers in an efficient and robust way. As an application, I will show some simulations of the largest glacier of the Alps, the Aletsch Glacier, from the end of the little ice age to present-day and in to the 21st century with different plausible climate scenarios. Last, I will discuss some challenges in paleo-ice sheet modelling -- such as difficulties posed by long time scales, which requires a compromise between model accuracy and computational cost -- and show an application to reconstruct the trajectory of erratic boulders carried by the Rhone Glacier during the last glacial maximum.
Senior Research Fellow, Antarctic Research Centre, VUW, NZ
From Snowflakes to Ice Sheets: why we need a multi-scale approach to understand past, present and future of the cryosphere
Ice sheets both control global sea level and provide our best records of greenhouse gases in the past. Loss of land-based ice contributes much of the uncertainty in global sea level projections for the coming century. While our current estimates of ice sheet mass balance have vastly improved with the onset of satellite observations, large uncertainties remain in our projections of ice sheet volume and its contribution to sea level. To improve those projections, we need to improve our understanding of past changes and the relationships between greenhouse gases, global temperatures, and global sea level. Ice cores provide a rich archive of past atmospheric composition and temperature but the resolution of ice core data, especially in times of rapid climate change, is currently limited by the lack of understanding of small scale processes. These processes include a) metamorphism from snow to ice, b) post-depositional changes in the isotope composition of ice and c) changes in snow/ice albedo. These processes are not only dependent on ice physics, but also on the interaction of the ice with the atmosphere. Improvements in the accuracy and precision of ice core records documenting rapid changes in greenhouse gas concentration, and the associated climate variations and environmental conditions, would be a significant advance in our understanding of past and future climate and ice sheet behaviour. Here I present recent advances in process understanding at multiple scales underlining their importance for ice sheet mass balance.
10:30 – 11:30 – Dr. Guillaume Jouvet
Senior scientist, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETHZ
Glacial motion: From first observations to state-of-the-art modelling
Glacial motion governs the advance and the retreat of glaciers. It has long been debated whether the observed surface motion is the result of ice deformation or basal sliding over the bedrock. It is now recognized that both mechanisms play an important role in glacier motion, depending on conditions at the glacier bed. In this presentation, I will first present how glacial motion is commonly modelled by using non-Newtonian fluid mechanics. This involves overcoming several numerical challenges in solving the underlying equations with complex and time-changing geometries that are characteristic of mountain glaciers. Here I will present an Eulerian method that can tackle these difficulties and simulate the time evolution of glaciers in an efficient and robust way. As an application, I will show some simulations of the largest glacier of the Alps, the Aletsch Glacier, from the end of the little ice age to present-day and in to the 21st century with different plausible climate scenarios. Last, I will discuss some challenges in paleo-ice sheet modelling -- such as difficulties posed by long time scales, which requires a compromise between model accuracy and computational cost -- and show an application to reconstruct the trajectory of erratic boulders carried by the Rhone Glacier during the last glacial maximum.
Practical information
- General public
- Free
Organizer
- ENAC
Contact
- Cristina Perez