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| Titel |
Conventional versus reference-surface mass balance |
| VerfasserIn |
M. Huss, R. Hock, A. Bauder, M. Funk |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250071432
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| Zusammenfassung |
| Glacier surface mass balance evaluated over the actual glacier geometry (conventional mass
balance) depends not only on climatic variations, but also on the dynamic adjustment of
glacier geometry. Therefore, it has been proposed that reference-surface balances calculated
over a constant glacier hypsometry and area are better suited for climatic interpretation. This
study addresses the question whether glacier monitoring programs should evaluate rather
reference-surface than conventional mass balances, and what can be learnt from a joint
analysis of these data sets.
We present a comparison of 82-year modelled time series (1926-2008) of conventional
and reference-surface balance for 36 Swiss glaciers. Over this time period the investigated
glaciers have lost 22% of their area and ice surface elevation close to the current glacier
terminus has decreased by 78 m on average. Mean conventional balance of the period
2000-2008 was –0.91 m w.e. a-1, and is 0.14 m w.e. a-1 less negative than the
reference-surface balance evaluated over the geometry of the first available Digital Elevation
Model (around 1930). About half of the negative (stabilizing) feedback on mass balance
due to glacier terminus retreat is compensated by more negative mass balances
due to surface lowering. Short-term climatic variability is clearly reflected in the
conventional mass balance series, however the magnitude of the long-term negative
trend is underestimated compared to that found in the reference-surface balance
series.
Both conventional and reference-surface specific balances show large spatial
variability among the 36 glaciers. Slope of the glacier tongue (lowermost 10%
of the glacier) calculated over the hypsometry of the first DEM best explains the
spatial variability in 82-year mean mass balances, and can be used to estimate the
difference between conventional and reference-surface balance of individual glaciers. |
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