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Adaptive Classification of Supra-Glacial Lakes on the West Greenland Ice Sheet
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
2013 (English)In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 6, no 4, 1998-2007 p.Article in journal (Refereed) Published
Abstract [en]

Meltwater is stored in supra-glacial lakes on the Greenland Ice Sheet. Connections between the melt water, ice sheet dynamics and the extent of the surface hydrological system have been observed. This highlights the importance of being able to study the surface hydrology over large spatial scales with a high temporal resolution. In this study, we develop an adaptive classification method to identify and map these supra-glacial lakes using high temporal resolution satellite images from the Moderate-resolution Imaging Spectroradiometer (MODIS) sensor. Surface reflectance images from 2007 are used to extract information about the lakes, their morphologies and their surroundings. Using a multiclass approach we can recognize lake types that have previously been difficult to classify, such as deep lakes, lakes within cryoconite areas and lakes with floating ice. Given significant increases in melting in recent years relative to the long term record the inclusion of deep lakes might prove particularly important.

Place, publisher, year, edition, pages
2013. Vol. 6, no 4, 1998-2007 p.
Keyword [en]
Landsat, MODIS, multispectral satellite imagery, object tracking, remote sensing, remote sensing applications
National Category
Climate Research
Research subject
Physical Geography
Identifiers
URN: urn:nbn:se:su:diva-84503DOI: 10.1109/JSTARS.2012.2233722ISI: 000322453800019OAI: oai:DiVA.org:su-84503DiVA: diva2:580581
Available from: 2012-12-23 Created: 2012-12-23 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Remote sensing of supra-glacial lakes on the west Greenland Ice Sheet
Open this publication in new window or tab >>Remote sensing of supra-glacial lakes on the west Greenland Ice Sheet
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography and Quaternary Geology (INK), Stockholm University, 2012. 28 p.
Series
Dissertations from the Department of Physical Geography and Quaternary Geology, ISSN 1653-7211 ; 31
Keyword
Supra-glacial lakes, Greenland Ice Sheet, Ice melting, Remote sensing, SAR, MODIS, Time-series analysis
National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-74509 (URN)978-91-7447-465-7 (ISBN)
Public defence
2012-04-20, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.

Available from: 2012-03-29 Created: 2012-03-15 Last updated: 2013-04-02Bibliographically approved

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