Kvartære geosystemer

Modeling the isochronal layering of the Greenland Ice Sheet

PhD candidate: Alexios Theofilopoulos

Supervision: Andreas Born (University of Bergen), Lev Tarasov (Memorial University of Newfoundland and Labrador)

Project Period: September 2017 – August 2021

This PhD project is part of the Modelling Englacial Layers and Tracers (MELT) in Ice Sheets project, which is funded by Bergens forskningsstiftelse (BFS) (https://www.uib.no/fg/mgg/119475/bfs-melt)

The title of the PhD is “Modeling the isochronal layering of the Greenland Ice Sheet”. Its main objective is to develop a model that will simulate the behavior of the Greenland Ice Sheet (GrIS) in relation to snow accumulation and to use existing data to optimize this behavior. The model used in the current project is time based instead of space based and simulates each layer of the GrIS individually, hence the name isochronal. As time passes, more layers are added on the top of the ice sheet due to accumulation, a variable that is the model’s most important boundary condition. As a result, every layer corresponds to a different time period, with the newer ones being on the top near the surface, while the older ones on the bottom. Every layer is a representation of the accumulation that occurred when the layer was created, but ice flow has altered its appearance during the evolution of the GrIS. The main objective of the current PhD will be to use the isochronal layer model in order to recreate how each layer was at the time of deposition, and thus find the amount of accumulation that occurred. The layers found on the GrIS today are measured by ice-penetrating radars mounted on aircrafts, a part of NASA’s IceBridge project. This radiostratigraphy data gives us important information about the depth of each layer on every location in Greenland. As part of the project, we will develop a data assimilation method that will manage to integrate this data to the isochronal model itself and thus we will systematically recreate the accumulation of the past climate. This will give us a well defined boundary condition, that will be used for a good and accurate simulation of the history of the GrIS, as well as important informations about the climate of the past.