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Remote sensing of s...
Remote sensing of supra-glacial lakes on the west Greenland Ice Sheet
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- Johansson, A. Malin (author)
- Stockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK),Glaciologi
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- Brown, Ian A., Dr. (thesis advisor)
- Stockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK)
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- Jansson, Peter, Prof. (thesis advisor)
- Stockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK)
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- Kleman, Johan, Prof. (thesis advisor)
- Stockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK)
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- Ahlstrøm, Andreas, Dr. (opponent)
- Geological Survey of Denmark and Greenland
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(creator_code:org_t)
- ISBN 9789174474657
- Stockholm : Department of Physical Geography and Quaternary Geology (INK), Stockholm University, 2012
- English 28 s.
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Series: Dissertations from the Department of Physical Geography and Quaternary Geology, 1653-7211 ; 31
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Abstract
Subject headings
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- The Greenland Ice Sheet is the largest ice sheet in the northern hemisphere. Ongoing melting of the ice sheet, resulting in increased mass loss relative to the longer term trend, has raised concerns about the stability of the ice sheet. Melt water generated at the surface is temporarily stored in supra-glacial lakes on the ice sheet. Connections between melt water generation, storage and ice sheet dynamics highlight the importance of the surface hydrological system.In this thesis different methods are used that improve our ability to observe the supra-glacial lake system on the west Greenland Ice Sheet. This region of the Greenland Ice Sheet has the most extensive supra-glacial hydrological system with a dense network of streams connecting lakes that can exceed several square kilometres in area. Synthetic Aperture Radar (SAR) and visible-near infrared (VNIR) images are used to explore the potential of different sensor systems for regular observations of the supra-glacial lakes. SAR imagery is found to be a useful complement to VNIR data. VNIR data from moderate resolution sensors are preferred as these provide high temporal resolution data, ameliorating problems with cloud cover.The dynamic nature of the lakes makes automated classification difficult and manual mapping has been widely used. Here a new method is proposed that improves on existing methods by automating the identification and classification of lakes, and by introducing a flexible system that can capture the full range of lake forms. Applying our new method we are better able to analyse the evolution of lakes over a number of melt seasons. We find that lakes initiate after approximately 40 positive degree days. Most lakes exist for less than 20 days before draining, or later in the season, and less often, freezing over. Using the automated method developed in this thesis lakes have been mapped in imagery from 2001–2010 at approximately five day intervals.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)
Keyword
- Supra-glacial lakes
- Greenland Ice Sheet
- Ice melting
- Remote sensing
- SAR
- MODIS
- Time-series analysis
- Physical Geography
- naturgeografi
Publication and Content Type
- vet (subject category)
- dok (subject category)
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