Trimline Mapping from Multispectral Landsat ETM+ Imagery
Multispectral Landsat ETM+ imagery is used to study the ice-marginal region in the vicinity of Jakobshavn Isfjord, west Greenland. In particular, the trimline indicating margin retreat since the maximum stand attained during the Little Ice Age maximum is reconstructed, and compared with earlier maps...
| Published in: | Géographie physique et Quaternaire |
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| Main Authors: | , , |
| Format: | Text |
| Language: | English |
| Published: |
Les Presses de l'Université de Montréal
2005
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| Subjects: | |
| Online Access: | http://id.erudit.org/iderudit/013736ar https://doi.org/10.7202/013736ar |
| Summary: | Multispectral Landsat ETM+ imagery is used to study the ice-marginal region in the vicinity of Jakobshavn Isfjord, west Greenland. In particular, the trimline indicating margin retreat since the maximum stand attained during the Little Ice Age maximum is reconstructed, and compared with earlier maps based on aerial photogrammetry and ground surveys. Applying supervised classification, fourteen different surface types were identified, ranging from snow and ice, debris-covered ice and water with differing turbidities, to different types of vegetative landcover. After similar classes were merged into five, distinctively different classes, a digitized geomorphologic map was used to assess the accuracy of the classification. The positional accuracy of the trimline was checked by using results from a GPS survey along northern slope of the Jakobshavn fjord. By merging three spectral bands with the panchromatic band, a pan-sharpened image with a spatial resolution of 15 m is obtained that clearly shows morphological features on the ice surface, as well as increased resolution of glacial geomorphology. La zone proglaciaire de la région de Jakobshavn Isfjorf, au Groenland occidental, est étudiée par l’imagerie multispectrale Landsat ETM+, avec un accent sur la limite atteinte par les glaces durant le Petit Âge Glaciaire. L’extension maximale des glaces est reconstituée par télédétection satellitaire et comparée aux données cartographiques basées sur la photogrammétrie et des mesures de terrain. Une classification dirigée a permis d’identifier 14 types de surfaces allant de la neige et de la glace, avec ou sans débris en surface, à divers types de couverture végétale, en passant par divers degrés de turbidité de l’eau. Une carte morphologique digitale de synthèse, avec cinq classes distinctes, est produite pour déterminer la justesse de la classification. La précision de l’emplacement de la trimline est validée par des mesures au GPS le long du versant nord du fjord de Jakobshavn. Après la fusion de trois bandes ... |
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