Seasonal dynamics of Petermann Glacier, Greenland
Abstract
Seasonal speed up of glaciers in northern Greenland have been observed in satellite data, but the physical driver is unclear. As an example, for Petermann Glacier we now observe a systemic 15% acceleration each summer. Approximately 4% of Greenland's total annual ice discharge is from Petermann. Although it is not undergoing a rapid retreat at present, Petermann started accelerating after 2010 and lost 35% of its ice floating extension. We use a combination of remote sensing and modeling techniques to examine possible physical mechanisms for seasonality in glacier velocity. Time series of ice front position (Landsat-8), ice velocity (Sentinel-1a/b), and grounding line position (Cosmo SkyMed) have been assembled from satellite observations for the time period 1996-present. Starting from an initial state in 2007, we model ice velocity using the Ice Sheet System Model (ISSM) and compare the results with the observed velocity time series. One of the drivers that we investigate is changes in basal conditions. To determine whether the inferred changes are realistic, we use the Glacier Drainage System model, GlaDS, with daily surface mass balance input data from MAR (Modèle Atmosphérique Régional) to calculate the effective pressure at the ice-bedrock interface throughout the melt season. Effective pressure is incorporated into ISSM using a friction law, and several different friction laws are tested to examine the relationship between subglacial hydrology and ice velocity. We also investigate the role of time-dependent grounding line position and time-dependent ice front position. We conclude on the role of these various physical processes on the observed temporal variability in speed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMC020.0006E
- Keywords:
-
- 0720 Glaciers;
- CRYOSPHERE;
- 0728 Ice shelves;
- CRYOSPHERE;
- 0730 Ice streams;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE