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Université de Fribourg

The firn meltwater retention model intercomparison project (retmip) : evaluation of nine firn models at four weather station sites on the greenland ice sheet

Vandecrux, Baptiste ; Mottram, Ruth ; Langen, Peter L. ; Fausto, Robert S. ; Olesen, Martin ; Stevens, C. Max ; Verjans, Vincent ; Leeson, Amber ; Ligtenberg, Stefan ; Munneke, Peter Kuipers ; Marchenko, Sergey ; Pelt, Ward van ; Meyer, Colin R. ; Simonsen, Sebastian B. ; Heilig, Achim ; Samimi, Samira ; Marshall, Shawn ; Machguth, Horst ; MacFerrin, Michael ; Niwano, Masashi ; Miller, Olivia ; Voss, Clifford I. ; Box, Jason E.

In: The Cryosphere, 2020, vol. 14, no. 11, p. 3785-3810

Perennial snow, or firn, covers 80 % of the Greenland ice sheet and has the capacity to retain surface meltwater, influencing the ice sheet mass balance and contribution to sea-level rise. Multilayer firn models are traditionally used to simulate firn processes and estimate meltwater retention. We present, intercompare and evaluate outputs from nine firn models at four sites that represent...

Université de Fribourg

Worldwide version-controlled database of glacier thickness observations

Welty, Ethan ; Zemp, Michael ; Navarro, Francisco ; Huss, Matthias ; Fürst, Johannes J. ; Gärtner-Roer, Isabelle ; Landmann, Johannes ; Machguth, Horst ; Naegeli, Kathrin ; Andreassen, Liss M. ; Farinotti, Daniel ; Li, Huilin ; GlaThiDa Contributors

In: Earth System Science Data, 2020, vol. 12, no. 4, p. 3039–3055

Although worldwide inventories of glacier area have been coordinated internationally for several decades, a similar effort for glacier ice thicknesses was only initiated in 2013. Here, we present the third version of the Glacier Thickness Database (GlaThiDa v3), which includes 3 854 279 thickness measurements distributed over roughly 3000 glaciers worldwide. Overall, 14 % of global...

Université de Fribourg

Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo

Tedstone, Andrew J. ; Cook, Joseph M. ; Williamson, Christopher J. ; Hofer, Stefan ; McCutcheon, Jenine ; Irvine-Fynn, Tristram ; Gribbin, Thomas ; Tranter, Martyn

In: The Cryosphere, 2020, vol. 14, no. 2, p. 521–538

One of the primary controls upon the melting of the Greenland Ice Sheet (GrIS) is albedo, a measure of how much solar radiation that hits a surface is reflected without being absorbed. Lower-albedo snow and ice surfaces therefore warm more quickly. There is a major difference in the albedo of snow-covered versus bare-ice surfaces, but observations also show that there is substantial spatio-...

Université de Fribourg

Rapid expansion of Greenland’s low-permeability ice slabs

MacFerrin, Mike ; Machguth, Horst ; As, Dirk van ; Charalampidis, C. ; Stevens, C. M. ; Heilig, A. ; Vandecrux, B. ; Langen, P. L. ; Mottram, R. ; Fettweis, Xavier ; Broeke, Michiel R. van den ; Pfeffer, W. T. ; Moussavi, M. S. ; Abdalati, W.

In: Nature, 2019, vol. 573, no. 7774, p. 403–407

In recent decades, meltwater runoff has accelerated to become the dominant mechanism for mass loss in the Greenland ice sheet1,2,3. In Greenland’s high- elevation interior, porous snow and firn accumulate; these can absorb surface meltwater and inhibit runoff4, but this buffering effect is limited if enough water refreezes near the surface to restrict percolation5,6. However, the influence...

Université de Fribourg

Ice-penetrating radar survey of the subsurface debris field at Camp Century, Greenland

Karlsson, Nanna B. ; Colgan, William T. ; Binder, Daniel ; Machguth, Horst ; Abermann, Jakob ; Hansen, Karina ; Pedersen, Allan Ø.

In: Cold Regions Science and Technology, 2019, vol. 165, p. 102788

The warming climate is changing the surface dynamics of the Greenland Ice Sheet, including the balance between snowfall and melt. Increasing surface melt impacts the structure of the relatively porous near-surface layer known as firn. Camp Century, a base abandoned in 1967, now comprises a subsurface debris field within the firn in Northwest Greenland. We collected 80 km of 100 or 250 MHz...