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SUMMARY:ENAC Seminar Series by Dr. Ruzica Dadic & Dr. Guillaume Jouvet
DTSTART:20181108T093000
DTEND:20181108T113000
DTSTAMP:20260922T014123Z
UID:be76ab9354319738fca47ec10c428f47fcd81280efbc6997629223f3
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Ruzica Dadic Dr. Guillaume Jouvet\n9:30 – 10:30 – Dr. 
 Ruzica Dadic\nSenior Research Fellow\, Antarctic Research Centre\, VUW\, N
 Z\n\nFrom Snowflakes to Ice Sheets: why we need a multi-scale approach to 
 understand past\, present and future of the cryosphere\n\nIce 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 pr
 ojections\, we need to improve our understanding of past changes and the r
 elationships between greenhouse gases\, global temperatures\, and global s
 ea 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 understandi
 ng of small scale processes. These processes include a) metamorphism from 
 snow to ice\, b) post-depositional changes in the isotope composition of i
 ce and c) changes in snow/ice albedo. These processes are not only depende
 nt on ice physics\, but also on the interaction of the ice with the atmosp
 here.  Improvements in the accuracy and precision of ice core records doc
 umenting rapid changes in greenhouse gas concentration\, and the associate
 d climate variations and environmental conditions\, would be a significant
  advance in our understanding of past and future climate and ice sheet beh
 aviour. Here I present recent advances in process understanding at multipl
 e scales underlining their importance for ice sheet mass balance.\n \n \
 n10:30 – 11:30 – Dr. Guillaume Jouvet\nSenior scientist\, Laboratory o
 f Hydraulics\, Hydrology and Glaciology (VAW)\, ETHZ\n\nGlacial motion: Fr
 om first observations to state-of-the-art modelling\n\nGlacial motion gove
 rns the advance and the retreat of glaciers. It has long been debated whet
 her the observed surface motion is the result of ice deformation or basal 
 sliding over the bedrock. It is now recognized that both mechanisms play a
 n important role in glacier motion\, depending on conditions at the glacie
 r bed. In this presentation\, I will first present how glacial motion is c
 ommonly modelled by using non-Newtonian fluid mechanics. This involves ove
 rcoming several numerical challenges in solving the underlying equations w
 ith complex and time-changing geometries that are characteristic of mounta
 in glaciers. Here I will present an Eulerian method that can tackle these 
 difficulties and simulate the time evolution of glaciers in an efficient a
 nd robust way. As an application\, I will show some simulations of the lar
 gest glacier of the Alps\, the Aletsch Glacier\, from the end of the littl
 e ice age to present-day and in to the 21st century with different plausib
 le climate scenarios. Last\, I will discuss some challenges in paleo-ice s
 heet modelling -- such as difficulties posed by long time scales\, which r
 equires a compromise between model accuracy and computational cost -- and 
 show an application to reconstruct the trajectory of erratic boulders carr
 ied by the Rhone Glacier during the last glacial maximum.
LOCATION:GC B3 30 https://plan.epfl.ch/?room=GCB330
STATUS:CONFIRMED
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