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| Titel |
Oblique photography for short-term monitoring of glacier mass balance |
| VerfasserIn |
Matthias Huss, Mazzal Stokvis, Martin Hoelzle |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056007
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| Zusammenfassung |
| Glacier mass balance is an important indicator of climate change. Mass balance monitoring
programs mostly report annual values because field measurements are laborious. For climatic
interpretation, the separation of the components of mass balance – accumulation and
melt – is important. This can be achieved by performing seasonal mass balance
surveys. However, the monthly or even daily glacier mass change over one year,
which is crucial for analyzing e.g. the importance of glacier melt contribution to the
hydrological cycle, can so far only be modelled, and not be easily observed directly in the
field.
Here, we outline a method that allows a temporally continuous monitoring of glacier mass
balance over the summer season. The method is primarily based on repeated digital
photography of the glacier, i.e. a data source that can be acquired without direct field site
access. The snowline in selected photographs of an automatic camera is delineated, and the
images are deskewed, orthorectified and georeferenced. Thus, the percentage of the glacier
covered with snow can be determined. The relation between glacier-wide mass balance and
the snow-covered area fraction (SAF) mainly depends on (1) the quantity and the spatial
distribution of snow, and (2) the glacier geometry. Rating curves of the SAF versus glacier
mass balance are inferred using a mass balance model driven by daily meteorological
variables averaged over the period 1961-1990. This allows an estimate of mass balance
evolution throughout the summer at high temporal resolution based on repeated terrestrial
photography.
The method is tested for Findelengletscher (13.4 km2), Switzerland, for the ablation
season of the year 2010. Direct mass balance measurements using the glaciological method
provide an independent data set for validating mass balances estimated using repeated
oblique photographs. A good agreement is found indicating the potential of the presented
method for high-resolution mass balance monitoring of remote or inaccessible glaciers. We
present an application to Gornergletscher (39.0 km2), Switzerland, the second largest glacier
of the European Alps. Using repeated photography for 2004-2009, glacier-wide mass balance
and the dynamics of snow and ice melt throughout the summer are determined for six years. |
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