Université de Fribourg

Strong contrast in mass and energy balance between a coastal mountain glacier and the Greenland ice sheet

Abermann, Jakob ; As, Dirk Van ; Wacker, Stefan ; Langley, Kirsty ; Machguth, Horst ; Fausto, Robert Schjøtt

In: Journal of Glaciology, 2019, vol. 65, no. 250, p. 263–269

We show a strong difference in surface mass and energy balance of a mountain glacier and two sites on the ice sheet at 64°N in West Greenland using stake and automated weather station observations. Net surface mass balance is on average 2.2 m w.e. less negative at the coast compared with the ice sheet in the same elevation. We find a larger energy turnover at the ice sheet margin on...

Université de Fribourg

Elevation changes of the Holm Land Ice Cap, northeast Greenland, from 1978 to 2012–2015, derived from high-resolution digital elevation models

Albedyll, Luisa von ; Machguth, Horst ; Nussbaumer, Samuel U. ; Zemp, Michael

In: Arctic, Antarctic, and Alpine Research, 2018, vol. 50, no. 1, p. e1523638

Greenland’s peripheral glaciers and ice caps are key indicators of climate change in the Arctic, but quantitative observational data of their recent evolution are sparse. Three recently released high-resolution digital elevation models (DEMs)—AeroDEM (based on images from 1978 to 1987), ArcticDEM (2012–2015), and TanDEM-X (2010–2014)—provide the possibility to calculate elevation...

Université de Fribourg

Changes in Greenland’s peripheral glaciers linked to the North Atlantic Oscillation

Bjørk?, A. A. ; Aagaard, S. ; Lütt, A. ; Khan, S. A. ; Box, J. E. ; Kjeldsen?, K. K. ; Larsen, N. K. ; Korsgaard?, N. J. ; Cappelen, J. ; Colgan, W. T. ; Machguth, Horst ; Andresen, C. S. ; Peings, Y. ; Kjær, K. H.

In: Nature Climate Change, 2018, vol. 8, no. 1, p. 48–52

Glaciers and ice caps peripheral to the main Greenland Ice Sheet contribute markedly to sea-level rise1,2,3. Their changes and variability, however, have been difficult to quantify on multi-decadal timescales due to an absence of long-term data4. Here, using historical aerial surveys, expedition photographs, spy satellite imagery and new remote-sensing products, we map glacier length...

Université de Fribourg

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

Cohen, Denis ; Gillet-Chaulet, Fabien ; Haeberli, Wilfried ; Machguth, Horst ; Fischer, Urs H.

In: The Cryosphere, 2018, vol. 12, no. 8, p. 2515–2544

At the Last Glacial Maximum (LGM), the Rhine glacier in the Swiss Alps covered an area of about 16000km2. As part of an integrative study about the safety of repositories for radioactive waste under ice age conditions in Switzerland, we modeled the Rhine glacier using a thermodynamically coupled three-dimensional, transient Stokes flow and heat transport model down to a horizontal resolution...

Université de Fribourg

The abandoned ice sheet base at Camp Century, Greenland, in a warming climate

Colgan, William ; Machguth, Horst ; MacFerrin, Mike ; Colgan, Jeff D. ; As, Dirk van ; MacGregor, Joseph A.

In: Geophysical Research Letters, 2016, vol. 43, no. 15, p. 8091–8096

In 1959 the U.S. Army Corps of Engineers built Camp Century beneath the surface of the northwestern Greenland Ice Sheet. There they studied the feasibility of deploying ballistic missiles within the ice sheet. The base and its wastes were abandoned with minimal decommissioning in 1967, under the assumption they would be preserved for eternity by perpetually accumulating snowfall. Here we show...

Université de Fribourg

A consensus estimate for the ice thickness distribution of all glaciers on Earth

Farinotti, Daniel ; Huss, Matthias ; Fürst, Johannes J. ; Landmann, Johannes ; Machguth, Horst ; Maussion, Fabien ; Pandit, Ankur

In: Nature Geoscience, 2019, vol. 12, no. 3, p. 168–173

Knowledge of the ice thickness distribution of the world’s glaciers is a fundamental prerequisite for a range of studies. Projections of future glacier change, estimates of the available freshwater resources or assessments of potential sea-level rise all need glacier ice thickness to be accurately constrained. Previous estimates of global glacier volumes are mostly based on scaling...

Université de Fribourg

A snow density dataset for improving surface boundary conditions in greenland ice sheet firn modeling

Fausto, Robert S. ; Box, Jason E. ; Vandecrux, Baptiste ; As, Dirk van ; Steffen, Konrad ; MacFerrin, Michael J. ; Machguth, Horst ; Colgan, William ; Koenig, Lora S. ; McGrath, Daniel ; Charalampidis, Charalampos ; Braithwaite, Roger J.

In: Frontiers in Earth Science, 2018, vol. 6, p. -

The surface snow density of glaciers and ice sheets is of fundamental importance in converting volume to mass in both altimetry and surface mass balance studies, yet it is often poorly constrained. Site-specific surface snow densities are typically derived from empirical relations based on temperature and wind speed. These parameterizations commonly calculate the average density of the top...

Université de Fribourg

Reconstructions of the 1900–2015 Greenland ice sheet surface mass balance using the regional climate MAR model

Fettweis, Xavier ; Box, Jason E. ; Agosta, Cécile ; Amory, Charles ; Kittel, Christoph ; Lang, Charlotte ; As, Dirk van ; Machguth, Horst ; Gallée, Hubert

In: The Cryosphere, 2017, vol. 11, no. 2, p. 1015–1033

With the aim of studying the recent Greenland ice sheet (GrIS) surface mass balance (SMB) decrease relative to the last century, we have forced the regional climate MAR (Modèle Atmosphérique Régional; version 3.5.2) model with the ERA-Interim (ECMWF Interim Re-Analysis; 1979–2015), ERA-40 (1958–2001), NCEP–NCARv1 (National Centers for Environmental Prediction–National Center for...

Université de Fribourg

Estimating the volume of glaciers in the Himalayan–Karakoram region using different methods

Frey, H. ; Machguth, Horst ; Huss, Matthias ; Huggel, C. ; Bajracharya, S. ; Bolch, T. ; Kulkarni, A. ; Linsbauer, Andreas ; Salzmann, Nadine ; Stoffel, Markus

In: The Cryosphere, 2014, vol. 8, no. 6, p. 2313–2333

Ice volume estimates are crucial for assessing water reserves stored in glaciers. Due to its large glacier coverage, such estimates are of particular interest for the Himalayan–Karakoram (HK) region. In this study, different existing methodologies are used to estimate the ice reserves: three area–volume relations, one slope-dependent volume estimation method, and two ice-thickness...

Université de Fribourg

A database of worldwide glacier thickness observations

Gärtner-Roer, I. ; Naegeli, K. ; Huss, Matthias ; Knecht, T. ; Machguth, Horst ; Zemp, Michael

In: Global and Planetary Change, 2014, vol. 122, p. 330–344

One of the grand challenges in glacier research is to assess the total ice volume and its global distribution. Over the past few decades the compilation of a world glacier inventory has been well-advanced both in institutional set-up and in spatial coverage. The inventory is restricted to glacier surface observations. However, although thickness has been observed on many glaciers and ice caps...