Master thesis colloquium – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2009 > Master thesis colloquium

Master thesis colloquium

Friday, February 6th, Maria Mygind presents her master thesis. The title of the thesis is "Modelling of Geothermal Heat under the Greenland Ice Sheet by Inversion of Basal Melt Rates".

The talk will be in danish.

Supervisors: Dorthe Dahl-Jensen and Klaus Mosegaard, University  of Copenhagen
Censor: Peter Aakjær, DMI

The aim of this thesis is to model the present day geothermal heat in the Earth's crust under the Greenland Ice Sheet. Based on estimations of the basal melt for the ice sheet in the northern Greenland, the task is to identify possible types of rock in the Earth's crust. Rock types can often be characterized by their radiogenic heat production and heat conductivity.

The area of interest is a 80 km long 2D profile of the Earth's crust, crossing NorthGRIP and going along the NNW-trending ice ridge from GRIP. In this area the basal melt rate fluctuates more rapidly than usual. The geothermal heat flux can be deduced from the basal melt rate and this leads to a heat flux of 121 - 231 mW/m2. This is much higher than previous found values in Greenland for example of 51.3 mW/m2 at GRIP and of ~65 mW/m2 for the average of the Earth's continents.

The temperature for the 2D profile is found by a numerical solution of the heat conduction equation. From the temperature gradient at the Earth's surface the geothermal heat flux can be calculated and converted into basal melt rate for the ice sheet. The unknown input parameters to the heat conduction equation are the heat productions in the crust. They are estimated by an inverse Monte Carlo method and observations of the basal melt rate are used to constrain the inversion.