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| Titel |
Changes in glacier equilibrium-line altitude in the western Alps from 1984 to 2010: evaluation by remote sensing and modeling of the morpho-topographic and climate controls |
| VerfasserIn |
A. Rabatel, A. Letréguilly, J.-P. Dedieu, N. Eckert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 7, no. 5 ; Nr. 7, no. 5 (2013-09-24), S.1455-1471 |
| Datensatznummer |
250085160
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| Publikation (Nr.) |
 copernicus.org/tc-7-1455-2013.pdf |
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| Zusammenfassung |
| We present time series of equilibrium-line altitude (ELA) measured from the
end-of-summer snow line altitude computed using satellite images, for 43
glaciers in the western Alps over the 1984–2010 period. More than 120
satellite images acquired by Landsat, SPOT and ASTER were used. In parallel,
changes in climate variables, summer cumulative positive degree days (CPDD)
and winter precipitation, were analyzed over the same time period using 22
weather stations located inside and around the study area. Assuming a
continuous linear trend over the study period: (1) the average ELA of the 43
glaciers increased by about 170 m; (2) summer CPDD increased by about 150
PDD at 3000 m a.s.l.; and (3) winter precipitation remained rather
stationary. Summer CPDD showed homogeneous spatial and temporal variability;
winter precipitation showed homogeneous temporal variability, but some
stations showed a slightly different spatial pattern. Regarding ELAs,
temporal variability between the 43 glaciers was also homogeneous, but
spatially, glaciers in the southern part of the study area differed from
glaciers in the northern part, mainly due to a different precipitation
pattern. A sensitivity analysis of the ELAs to climate and
morpho-topographic variables (elevation, aspect, latitude) highlighted the
following: (1) the average ELA over the study period of each glacier is
strongly controlled by morpho-topographic variables; and (2) the interannual
variability of the ELA is strongly controlled by climate variables, with the
observed increasing trend mainly driven by increasing temperatures, even if
significant nonlinear, low-frequency fluctuations appear to be driven by
winter precipitation anomalies. Finally, we used an expansion of Lliboutry's
approach to reconstruct fluctuations in the ELA of any glacier of the study
area with respect to morpho-topographic and climate variables, by
quantifying their respective weight and the related uncertainties in a
consistent manner within a hierarchical Bayesian framework. This method was
tested and validated using the ELA measured on the satellite images. |
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