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

• Main Authors: Janssens, I., Huybrechts, Philippe
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2000
• Subjects: Greenland; Annals of Glaciology; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/1551/; https://epic.awi.de/id/eprint/1551/1/Jns9999a.pdf; https://hdl.handle.net/10013/epic.12141; https://hdl.handle.net/10013/epic.12141.d001

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.