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| Titel |
Modeling mass balance of a tropical glacier in the Peruvian Andes |
| VerfasserIn |
Wolfgang Gurgiser, Ben Marzeion, Martin Ortner, Georg Kaser  |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089592
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| Publikation (Nr.) |
 EGU/EGU2014-3798.pdf |
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| Zusammenfassung |
| Glacier mass balance models ranging in complexity from regression models to process based
energy balance models have been applied on tropical glaciers in South America for
glaciological and hydrological issues.
Within a case study on Shallap glacier in the Peruvian Cordillera Blanca we calculated 4
years of glacier mass and energy balance, using a process based model at high spatial and
temporal resolution. We investigated the contribution of the terms of the energy fluxes to
surface melt at seasonal and annual time scales. We compared the calculated mass balance
values obtained from the process based model with the ones obtained from a basic
temperature based regression model for monthly and annual time scales. The results match
surprisingly well for the entire period with decreasing model skill on increasing temporal
resolution.
As the 4 year test period was characterized by relatively low variability in annual mean
temperature, we increased annual temperature variability by ± 1° C for a 2 year test period,
which is a likely upper limit of annual temperature variation expectable from long term
records and within possible future climate conditions. We again compared the model outputs
and found that the process based model markedly responds to the change in atmospheric
forcing. In contrast, the regression model does only show minor response to increased
temperature variability.
We show that missing information (e.g., area altitude distribution) and badly captured
processes (e.g., temperature impacts on surface albedo) within the regression model are the
most likely reasons for the different model behaviors. While considering topographic
information within simple models is possible, we conclude that high variability in surface
albedo (typical for ablation zones of a Tropical glaciers) poses a tough challenge for
calculating surface mass balance or melt water production on seasonal to monthly time
scales with temperature based regression models. On multi-annual time steps, we
demonstrate that for the present glacier extent, increased temperature variability (with
constant mean temperature) would decrease mean surface albedo. This impact is not
captured by simple regression models and could lead to lower model skills for future
or past climate conditions compared to present days calibration and evaluation
periods. |
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