The treatment of meltwater retention in mass-balance parameterisations of the Greenland ice sheet


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phuybrechts [ at ] awi-bremerhaven.de

Abstract

Retention of melt-water runoff by percolation and/ or refreezing in the snowpack cannot be neglected when studying the surface mass balance of the Greenlandice sheet. In this paper, we make a detailed comparison of several treatments proposed in the literature to account for this process in large-scale mass-balanceparameterizations. The melt on the Greenland ice sheet is calculated with a revised degree-day model using updated datasets of surface elevation and precipitationrate on a 5 km grid. Crucial model parameters are recalibrated by comparing mass-balance characteristics with available observations on a regional basis. Wediscuss the role of meltwater retention in the light of the overall mass-balance of the Greenland ice sheet and its sensitivity to climatic change, and displaypatterns of effective retention fractions for the various methods. As a main conclusion, it appears that overall results are quite similar for the various models, butthat meltwater retention has a large spatial variation not described by the simple treatments. Using the most comprehensive retention model, the sensitivity of therunoff is found to be +0.35 mm/ deg C of sea-level change per year. We also present a new map of the different zones (facies) that characterize the accumulationarea of the Greenland ice sheet, that is useful for interpreting field data and calibrating satellite observations.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
1551
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Janssens, I. and Huybrechts, P. (2000): The treatment of meltwater retention in mass-balance parameterisations of the Greenland ice sheet , Annals of Glaciology, 31 , pp. 133-140 .


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