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Kvartære geosystemer

Masterprosjekt V19 KGS

Masterprosjekt vår 2019 ved GEO - Kerim Nisancioglu

Geometric controls of fjord glacier dynamics

Project description

Most major ice caps and ice sheets (past and present) are drained by a few fast-flowing marine terminating glaciers. A large number of these glaciers meet the ocean in long fjords with complex geometry. It is well known that the geometry of these fjords influence stability and retreat dynamics of these glaciers, and in particular glaciers with floating ice tongues at the front. However, the impact of different fjord geometries has not been adequately quantified.

Providing a better understanding of the dynamics of such marine glaciers is of utmost importance. By testing the impact of different simplified fjord geometries in a state of the art ice flow model, we will be able to investigate the interplay between fjord geometry and ice dynamics. This work will provide the tools to better constrain the potential future retreat of present-day outlet glaciers, as well as help reconstruct past glacier retreat in the fjords of Norway, Greenland and elsewhere. A better understanding of the potential stable position of grounding lines (the location where the glacier becomes afloat) will also prove useful in the prediction of moraine locations.

Hypothesis (scientific problem)
Fjord geometry, and in particular the lateral constrains in the form of variations in fjord width, dominate the evolution (retreat and advance) of marine terminating glaciers on long timescales (decadal to centennial). As a consequence, if a retreat or advance is triggered by either atmosphere or ocean warming, knowing the detailed geometry of the fjord will dictate the long term evolution of marine terminating glaciers, including the location of pinning points and areas of rapid retreat.

Test (work)
The dynamics of fjord glaciers and in particular their grounding lines (where the glacier becomes afloat) is known to be highly dependent on the underlying bedrock topography. However, few studies have investigated the impact of changing fjord width. We propose a project to better constrain these geometrical effects through the application of a state of the art ice flow model on synthetic geometries. By applying synthetic geometries we can limit the computing cost of the model and provide critical insights on key parameters constraining the ice flow model and providing more robust predictions of future glacier evolution.

The tasks of the candidate will be to set-up, run and analyse simulations with a state of the art ice-sheet model (ISSM). Exploratory work has already been undertaken using a simplified flow line model during the PhD of Henning Åkesson at GEO. This work will serve as a base to develop a three-dimensional investigation using a more complex ice flow model. The candidate will be co-supervised by K.H. Nisancioglu and B. De Fleurian at UiB. The co- supervising by H. Åkesson at will also open the opportunity for research stays at the Bert Bolin Centre for climate research at Stockholm University.

Prereqesites

Strong mathematical and numerical skills.

Proposed course plan during the master degree

GEOF211 (10 ects), GEOV223 (10 ects), GEOV230 (10 ects)
GEOV300 (5 ects), GEOV302 (10 ects), GEOV325 (5 ects)

We also encourage the candidate to follow relevant UNIS courses (e.g. AG325 and AG340), in addition to the Karthaus summer school.