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

Assessment of evolution and risks of glacier lake outbursts in the Djungarskiy Alatau, Central Asia, using Landsat imagery and glacier bed topography modelling

Kapitsa, Vassiliy ; Shahgedanova, Maria ; Machguth, Horst ; Severskiy, Igor ; Medeu, Akhmetkal

In: Nat. Hazards Earth Syst. Sci., 2017, vol. 17, no. 10, p. 1837–1856

Changes in the abundance and area of mountain lakes in the Djungarskiy (Jetysu) Alatau between 2002 and 2014 were investigated using Landsat imagery. The number of lakes increased by 6.2 % from 599 to 636 with a growth rate of 0.51 % a−1. The combined areas were 16.26 ± 0.85 to 17.35 ± 0.92 km2 respectively and the overall change was within the uncertainty of measurements....

Université de Fribourg

Three decades of volume change of a small greenlandic glacier using ground penetrating radar, structure from motion, and aerial photogrammetry

Marcer, M. ; Stentoft, P. A. ; Bjerre, E. ; Cimoli, E. ; Bjørk, A. ; Stenseng, L. ; Machguth, Horst

In: Arctic, Antarctic, and Alpine Research, 2017, vol. 49, no. 3, p. 411–425

Glaciers in the Arctic are losing mass at an increasing rate. Here we use surface topography derived from Structure from Motion (SfM) and ice volume from ground penetrating radar (GPR) to describe the 2014 state of Aqqutikitsoq glacier (2.85 km2) on Greenland's west coast. A photogrammetrically derived 1985 digital elevation model (DEM) was subtracted from a 2014 DEM obtained using land-based...

Université de Fribourg

Re-establishing glacier monitoring in Kyrgyzstan and Uzbekistan, Central Asia

Hoelzle, Martin ; Azisov, Erlan ; Barandun, Martina ; Huss, Matthias ; Farinotti, Daniel ; Gafurov, Abror ; Hagg, Wilfried ; Kenzhebaev, Ruslan ; Kronenberg, Marlene ; Machguth, Horst ; Merkushkin, Alexandr ; Moldobekov, Bolot ; Petrov, Maxim ; Saks, Tomas ; Salzmann, Nadine ; Schöne, Tilo ; Tarasov, Yuri ; Usubaliev, Ryskul ; Vorogushyn, Sergiy ; Yakovlev, Andrey ; Zemp, Michael

In: Geoscientific Instrumentation, Methods and Data Systems, 2017, vol. 6, no. 2, p. 397–418

Glacier mass loss is among the clearest indicators of atmospheric warming. The observation of these changes is one of the major objectives of the international climate monitoring strategy developed by the Global Climate Observing System (GCOS). Long-term glacier mass balance measurements are furthermore the basis for calibrating and validating models simulating future runoff of glacierised...

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

A tipping point in refreezing accelerates mass loss of Greenland’s glaciers and ice caps

Noël, B. ; Berg, W. J van de ; Lhermitte, S. ; Wouters, B. ; Machguth, Horst ; Howat, I. ; Citterio, M. ; Moholdt, G. ; Lenaerts, J. T. M. ; Broeke, M. R. van den

In: Nature Communications, 2017, vol. 8, p. 14730

Melting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote...

Université de Fribourg

A daily, 1 km resolution data set of downscaled Greenland ice sheet surface mass balance (1958–2015)

Noël, Brice ; Berg, Willem Jan van de ; Machguth, Horst ; Lhermitte, Stef ; Howat, Ian ; Fettweis, Xavier ; Broeke, Michiel R. van den

In: The Cryosphere, 2016, vol. 10, no. 5, p. 2361–2377

This study presents a data set of daily, 1 km resolution Greenland ice sheet (GrIS) surface mass balance (SMB) covering the period 1958–2015. Applying corrections for elevation, bare ice albedo and accumulation bias, the high-resolution product is statistically downscaled from the native daily output of the polar regional climate model RACMO2.3 at 11 km. The data set includes all...

Université de Fribourg

Modelling glacier-bed overdeepenings and possible future lakes for the glaciers in the Himalaya—Karakoram region

Linsbauer, Andreas ; Frey, H. ; Haeberli, Winfried ; Machguth, Horst ; Azam, M. F. ; Allen, S.

In: Annals of Glaciology, 2016, vol. 57, no. 71, p. 119–130

Surface digital elevation models (DEMs) and slope-related estimates of glacier thickness enable modelling of glacier-bed topographies over large ice-covered areas. Due to the erosive power of glaciers, such bed topographies can contain numerous overdeepenings, which when exposed following glacier retreat may fill with water and form new lakes. In this study, the bed overdeepenings for ~28 000...

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

Mass balance re-analysis of Findelengletscher, Switzerland; benefits of extensive snow accumulation measurements

Sold, Leo ; Huss, Matthias ; Machguth, Horst ; Joerg, Philip C. ; Leysinger Vieli, Gwendolyn ; Linsbauer, Andreas ; Salzmann, Nadine ; Zemp, Michael ; Hoelzle, Martin

In: Front. Earth Sci. - Cryospheric Sciences, 2016, p. 18

A re-analysis is presented here of a 10 year mass balance series at Findelengletscher, a temperate mountain glacier in Switzerland. Calculating glacier-wide mass balance from the set of glaciological point balance observations using conventional approaches, such as the profile or contour method, resulted in significant deviations from the reference value given by the geodetic mass...