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| Titel |
Using daily air temperature thresholds to evaluate snow melting occurrence and amount on Alpine glaciers by T-index models: the case study of the Forni Glacier (Italy) |
| VerfasserIn |
A. Senese, M. Maugeri, E. Vuillermoz, C. Smiraglia, G. Diolaiuti |
| 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 ; 8, no. 5 ; Nr. 8, no. 5 (2014-10-22), S.1921-1933 |
| Datensatznummer |
250116328
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| Publikation (Nr.) |
 copernicus.org/tc-8-1921-2014.pdf |
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| Zusammenfassung |
Glacier melt conditions (i.e., null surface temperature and positive energy
budget) can be assessed by analyzing data acquired by a supraglacial
automatic weather station (AWS), such as the station installed on the
surface of Forni Glacier (Italian Alps). When an AWS is not present, the
assessment of actual melt conditions and the evaluation of the melt amount
is more difficult and simple methods based on T-index (or degree days)
models are generally applied. These models require the choice of a correct
temperature threshold. In fact, melt does not necessarily occur at daily air
temperatures higher than 0 °C. In this paper, we applied both
energy budget and T-index approaches with the aim of solving this issue.
We start by distinguishing between the occurrence of snowmelt and the
reduction in snow depth due to actual ablation (from snow depth data
recorded by a sonic ranger). Then we find the daily average temperature
thresholds (by analyzing temperature data acquired by an AWS on Forni
Glacier) which, on the one hand, best capture the occurrence of significant
snowmelt conditions and, on the other, make it possible, using the T-index,
to quantify the actual snow ablation amount. Finally we investigated the
applicability of the mean tropospheric lapse rate to reproduce air
temperature conditions at the glacier surface starting from data acquired by
weather stations located outside the glacier area.
We found that the mean tropospheric lapse rate allows for a good and reliable
reconstruction of glacier air temperatures and that the choice of an
appropriate temperature threshold in T-index models is a very important
issue. From our study, the application of the +0.5 °C
temperature threshold allows for a consistent quantification of snow ablation
while, instead, for detecting the beginning of the snow melting processes
a suitable threshold has proven to be at least −4.6 °C. |
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