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Université de Fribourg

Application and validation of long-range terrestrial laser scanning to monitor the mass balance of very small glaciers in the Swiss Alps

Fischer, Mauro ; Huss, Matthias ; Kummert, Mario ; Hoelzle, Martin

In: The Cryosphere, 2016, vol. 10, no. 3, p. 1279–1295

Due to the relative lack of empirical field data, the response of very small glaciers (here defined as being smaller than 0.5 km²) to current atmospheric warming is not fully understood yet. Investigating their mass balance, e.g. using the direct glaciological method, is a prerequisite to fill this knowledge gap. Terrestrial laser scanning (TLS) techniques operating in the near infrared...

Université de Fribourg

Calculating distributed glacier mass balance for the Swiss Alps from regional climate model output: A methodical description and interpretation of the results

Machguth, Horst ; Paul, Frank ; Kotlarski, Sven ; Hoelzle, Martin

In: Journal of Geophysical Research, 2009, vol. 114, p. D19106

This study aims at giving a methodical description of the use of gridded output from a regional climate model (RCM) for the calculation of glacier mass balance distribution for the perimeter of the Swiss Alps. The mass balance model runs at daily steps and 100 m spatial resolution, while the regional model (REMO) RCM provides daily grids (∼18 km resolution) of dynamically downscaled reanalysis...

Université de Fribourg

Change detection of bare-ice albedo in the Swiss Alps

Naegeli, Kathrin ; Huss, Matthias ; Hoelzle, Martin

In: The Cryosphere, 2019, vol. 13, no. 1, p. 397–412

Albedo feedback is an important driver of glacier melt over bare-ice surfaces. Light- absorbing impurities strongly enhance glacier melt rates but their abundance, composition and variations in space and time are subject to considerable uncertainties and ongoing scientific debates. In this study, we assess the temporal evolution of shortwave broadband albedo derived from 15 end-of-summer...

Université de Fribourg

Cross-comparison of albedo products for glacier surfaces derived from airborne and satellite (sentinel-2 and landsat 8) optical data

Naegeli, Kathrin ; Damm, Alexander ; Huss, Matthias ; Wulf, Hendrik ; Schaepman, Michael ; Hoelzle, Martin

In: Remote Sensing, 2017, vol. 9, no. 2, p. 110

Surface albedo partitions the amount of energy received by glacier surfaces from shortwave fluxes and modulates the energy available for melt processes. The ice- albedo feedback, influenced by the contamination of bare-ice surfaces with light- absorbing impurities, plays a major role in the melting of mountain glaciers in a warming climate. However, little is known about the spatial and...

Université de Fribourg

Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and ground ice occurrence in the Swiss Alps

Kenner, Robert ; Noetzli, Jeannette ; Hoelzle, Martin ; Raetzo, Hugo ; Phillips, Marcia

In: The Cryosphere, 2019, vol. 13, no. 7, p. 1925–1941

Mountain permafrost is invisible, and mapping it is still a challenge. Available permafrost distribution maps often overestimate the permafrost extent and include large permafrost-free areas in their permafrost zonation. In addition, the representation of the lower belt of permafrost consisting of ice-rich features such as rock glaciers or ice-rich talus slopes can be challenging. These...

Université de Fribourg

Distributed snow and rock temperature modelling in steep rock walls using Alpine3D

Haberkorn, Anna ; Wever, Nander ; Hoelzle, Martin ; Phillips, Marcia ; Kenner, Robert ; Bavay, Mathias ; Lehning, and Michael

In: The Cryosphere, 2017, vol. 11, no. 1, p. 585–607

In this study we modelled the influence of the spatially and temporally heterogeneous snow cover on the surface energy balance and thus on rock temperatures in two rugged, steep rock walls on the Gemsstock ridge in the central Swiss Alps. The heterogeneous snow depth distribution in the rock walls was introduced to the distributed, process-based energy balance model Alpine3D with a...

Université de Fribourg

Evidence of accelerated englacial warming in the Monte Rosa area, Switzerland/Italy

Hoelzle, Martin ; Darms, G. ; Lüthi, M. P. ; Suter, Stefan M.

In: The Cryosphere, 2011, vol. 5, no. 1, p. 231-243

A range of englacial temperature measurements was acquired in the Monte Rosa area at the border of Switzerland and Italy in the years 1982, 1991, 1994, 1995, 1999, 2000, 2003, 2007 and 2008. Englacial temperatures revealed no evidence of warming at the firn saddle of Colle Gnifetti at 4452 m a.s.l. between 1982 and 1991, the 1991 to 2000 period showed an increase of 0.05 °C per year at a depth...

Université de Fribourg

A full Stokes ice-flow model to assist the interpretation of millennial-scale ice cores at the high-Alpine drilling site Colle Gnifetti, Swiss/Italian Alps

Licciulli, Carlo ; Bohleber, Pascal ; Lier, Josef ; Gagliardini, Olivier ; Hoelzle, Martin ; Eisen, Olaf

In: Journal of Glaciology, 2020, vol. 66, no. 255, p. 35–48

The high-Alpine ice-core drilling site Colle Gnifetti (CG), Monte Rosa, Swiss/Italian Alps, provides climate records over the last millennium and beyond. However, the full exploitation of the oldest part of the existing ice cores requires complementary knowledge of the intricate glacio-meteorological settings, including glacier dynamics. Here, we present new ice-flow modeling studies of CG,...

Université de Fribourg

Glacier and runoff changes in the Rukhk catchment, upper Amu-Darya basin until 2050

Hagg, Wilfried ; Hoelzle, Martin ; Wagner, Stephan ; Mayr, Elisabeth ; Klose, Zbynek

In: Global and Planetary Change, 2013, vol. 110, Part A, p. 62–73

A conceptual hydrological model was set up in the upper Panj catchment, the main tributary of Amu-Darya river. After a manual calibration procedure involving model runs with different restrictions, the model reproduced both daily hydrographs of Tanimas river at the Rukhk gauging station (NSE = 0.86) and the snow water equivalent of the Irkht station (R2 = 0.85) in a very satisfactory way. Based...