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Titel |
From Doktor Kurowski's Schneegrenze to our modern glacier equilibrium line altitude (ELA) |
VerfasserIn |
R. J. Braithwaite |
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 ; 9, no. 6 ; Nr. 9, no. 6 (2015-11-18), S.2135-2148 |
Datensatznummer |
250116871
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Publikation (Nr.) |
copernicus.org/tc-9-2135-2015.pdf |
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Zusammenfassung |
Translated into modern terminology, Kurowski suggested in 1891 that the
equilibrium line altitude (ELA) of a glacier is equal to the mean altitude
of the glacier when the whole glacier is in balance between accumulation and
ablation. Kurowski's method has been widely misunderstood, partly due to
inappropriate use of statistical terminology by later workers, and has only
been tested by Braithwaite and Müller in a 1980 paper (for 32 glaciers).
I now compare Kurowski's mean altitude with balanced-budget ELA
calculated for 103 present-day glaciers with measured surface mass-balance
data. Kurowski's mean altitude is significantly higher (at 95 % level)
than balanced-budget ELA for 19 outlet and 42 valley glaciers, but not
significantly higher for 34 mountain glaciers. The error in Kurowski mean
altitude as a predictor of balanced-budget ELA might be due to generally
lower balance gradients in accumulation areas compared with ablation areas
for many glaciers, as suggested by several workers, but some glaciers have
higher gradients, presumably due to precipitation increase with altitude.
The relatively close agreement between balanced-budget ELA and mean altitude
for mountain glaciers (mean error – 8 m with standard deviation 59 m) may
reflect smaller altitude ranges for these glaciers such that there is less
room for effects of different balance gradients to manifest themselves. |
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