27 January, 2010 (16:00 GMT), 5 Merrion Square, Dublin 2.
Speaker: Ondrej Soucek, DIAS.
Title: Numerical modeling of ice sheet dynamics.
Abstract:
Ice sheets are masses of grounded ice, which evolve in regions where climatic conditions allow for long-term deposition of snow cover. Through a complex process of successive compaction inducing internal structure changes, glacier ice is formed, being one of the many known crystalline phases of solid water. At sufficiently long time scales, due to internal creep, glacier ice behaves as a non-Newtonian fluid. This fact enables us to describe and explain the evolution of ice-sheets at these time scales by means of continuum thermomechanics constructing a nonlinear-fluid model with geometry that is controlled by gravitationally driven creep flow that is coupled with thermal conditions inside the ice sheet, and by surface processes of accumulation, ablation and basal sliding. Since ice-sheets are typically flat, with the vertical-to-horizontal aspect ratio smaller than 1/100, a scaling approximation utilizing this fact is often adopted in the glaciological community, resulting in the so-called “shallow-ice” approximation (SIA). This approximation of ice flow enables to compute the ice-sheet velocity field, induced by gravity, semi-analytically, which represents an effective computational tool compared to more accurate approaches. During the last several years, however, the shallow-ice approximation is being slowly abandoned, as the effects of higher-order dynamics or even the exact solution to the ice-flow problem are looked for, typically, by means of advanced numerical techniques such as finiteelements or spectral methods. The increase of computational demands is, however, enormous compared to the SIA, making it problematic to implement these techniques for the large-scale evolutionary ice-sheet models. We therefore designed an iterative algorithm, capable of successive improvement of the SIA solution towards the exact solution, still possessing the SIA’s computational effectiveness. To demonstrate the applicability of our technique, we will present results from (i) the Ice-Sheet Model Intercomparison Project – Higher-Order Models (ISMIP-HOM), a benchmark focused on the evaluation of the non-shallow higher-order effects the on ice-sheet dynamics, (ii) from
the European Ice Sheet Modeling INiTiative (EISMINT) benchmark focused on investigating the large-scale characteristics of thermo-mechanically coupled ice-sheet models and (iii) from the EISMINT benchmark for Greenland Ice Sheet models.
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Last Updated: 22nd March 2016 by Anna
2010-01-27 – SEMINAR by Odrej Soucek: Numerical modeling of ice sheet dynamics
27 January, 2010 (16:00 GMT), 5 Merrion Square, Dublin 2.
Speaker: Ondrej Soucek, DIAS.
Title: Numerical modeling of ice sheet dynamics.
Abstract:
Ice sheets are masses of grounded ice, which evolve in regions where climatic conditions allow for long-term deposition of snow cover. Through a complex process of successive compaction inducing internal structure changes, glacier ice is formed, being one of the many known crystalline phases of solid water. At sufficiently long time scales, due to internal creep, glacier ice behaves as a non-Newtonian fluid. This fact enables us to describe and explain the evolution of ice-sheets at these time scales by means of continuum thermomechanics constructing a nonlinear-fluid model with geometry that is controlled by gravitationally driven creep flow that is coupled with thermal conditions inside the ice sheet, and by surface processes of accumulation, ablation and basal sliding. Since ice-sheets are typically flat, with the vertical-to-horizontal aspect ratio smaller than 1/100, a scaling approximation utilizing this fact is often adopted in the glaciological community, resulting in the so-called “shallow-ice” approximation (SIA). This approximation of ice flow enables to compute the ice-sheet velocity field, induced by gravity, semi-analytically, which represents an effective computational tool compared to more accurate approaches. During the last several years, however, the shallow-ice approximation is being slowly abandoned, as the effects of higher-order dynamics or even the exact solution to the ice-flow problem are looked for, typically, by means of advanced numerical techniques such as finiteelements or spectral methods. The increase of computational demands is, however, enormous compared to the SIA, making it problematic to implement these techniques for the large-scale evolutionary ice-sheet models. We therefore designed an iterative algorithm, capable of successive improvement of the SIA solution towards the exact solution, still possessing the SIA’s computational effectiveness. To demonstrate the applicability of our technique, we will present results from (i) the Ice-Sheet Model Intercomparison Project – Higher-Order Models (ISMIP-HOM), a benchmark focused on the evaluation of the non-shallow higher-order effects the on ice-sheet dynamics, (ii) from
the European Ice Sheet Modeling INiTiative (EISMINT) benchmark focused on investigating the large-scale characteristics of thermo-mechanically coupled ice-sheet models and (iii) from the EISMINT benchmark for Greenland Ice Sheet models.
Category: Geophysics Section News & Events
Happy Birthday! twitter.com/thecelticist/s…
The papers were 1) Affine Field Theory: conservation identitites and relation to Weyl and Eddington 2)The Union of the three fundamental fields (Gravitation, Menson, Electromagnetism) Which went on to secure worldwide acclaim. #DIASdiscovers
Date: 01 December 1943 Paper: The Irish Press Headline: Two Papers by Dr. Schroedinger Synopsis: 1943 was a busy year for Schroedinger. Not only did he deliver the "What is Life?" Lectures in @tcddublin in February in November he delivered two papers in the @RIAdawson (1/2)
Available to buy on the DIAS bookshop: books.dias.ie/index.php?main… (5/5) #DIASdiscovers #celtic #studies #twopatricks
"In the lives of St. Patrick, the two saints are invariably fused into one", said Prof. O'Rahilly in his lecture. The lecture was a condensation from O’Rahilly’s book “The two Patricks: a lecture on the history of Christianity in fifth-century Ireland”. (4/5)
He was known by his first name Patricius, which in later times would lead to confusion as he was succeeded by another apostle of the same name (Saint Patrick or Patricius in Latin). (3/5)
He spoke on "Palladius and Patrick". Palladius was the first bishop of the Christians of Ireland. (2/5)
Date: 21st March 1942 Paper: The Irish Press Headline: Palladius and Patrick | School Of Celtic Studies Lecture Synopsis: The first public lecture under the auspices of the School of Celtic Studies was delivered in Trinity College by Professor T. F. O'Rahilly in 1942. (1/5)
As part of our ongoing participation in the @HistFest we decided to take a look into the Irish Newspaper Archives and see where DIAS made it into print over the last 80 years. There were so many articles, the hardest part was selecting what we would post. We hope you enjoy!
@AReillyFailte @CultureNight @VisitDublin Thanks Antoinette! Glad you enjoyed 😊
Big thank you to @MartinaPQuinn of @helloalicepr for moderating the discussion, and of course to our panel @NeasaMcG @CormacORafferty and @laoneill111
@CormacORafferty "to cut yourself off from fundamental research means you could miss out on some of the biggest ideas"
@laoneill "it's our job as researchers to keep reminding governments how important basic research is" "For Dev basic research being carried out in Ireland was a badge of pride"
@NeasaMcG Schrödinger's work in causality was not well received by the religious authorities at the time At the same time DIAS did have Catholic priests working on research projects in the early days, so there was not the conflict you might think between science and religion
@laoneill111 Schrödinger was very popular in social circles in Dublin, a bit of a renaissance man
@CormacORafferty Schrödinger was gifted at explaining difficult concepts
@CormacORafferty on how unsuccessful work, in Schrödinger's case, unified field theory, is just as important part of science. And no one has managed to crack it yet! And not forgetting the cat
@laoneill111 how Schrödinger's book inspired scientists to change fields and result in the finding of the double helix.