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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

Near-surface ventilation as a key for modeling the thermal regime of coarse blocky rock glaciers

Pruessner, Luisa ; Phillips, Marcia ; Farinotti, Daniel ; Hoelzle, Martin ; Lehning, Michael

In: Permafrost and Periglacial Processes, 2018, vol. 29, no. 3, p. 152–163

In a changing climate, ice‐rich permafrost features such as rock glaciers will experience drastic changes. Modeling the heat transport through the blocky surface layer with its large interstitial pore spaces poses some challenges as various modes of non‐conductive heat transport—advective forms in particular—can occur. Here, we show that the 1D physics‐based model SNOWPACK can be...

Université de Fribourg

Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations

Barandun, Martina ; Huss, Matthias ; Usubaliev, Ryskul ; Azisov, Erlan ; Berthier, Etienne ; Kääb, Andreas ; Bolch, Tobias ; Hoelzle, Martin

In: The Cryosphere, 2018, vol. 12, no. 6, p. 1899–1919

Glacier surface mass balance observations in the Tien Shan and Pamir are relatively sparse and often discontinuous. Nevertheless, glaciers are one of the most important components of the high-mountain cryosphere in the region as they strongly influence water availability in the arid, continental and intensely populated downstream areas. This study provides reliable and continuous surface mass...

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

Mass balance observations and reconstruction for Batysh Sook Glacier, Tien Shan, from 2004 to 2016

Kenzhebaev, Ruslan ; Barandun, , Martina ; Kronenberg, Marlene ; Chen, Yaning ; Usubaliev, , Ryskul ; Hoelzle, Martin

In: Cold Regions Science and Technology, 2017, vol. 135, p. 76–89

In this study we present an analysis of measured annual mass balances for the period 2011 to 2016 and a reconstruction of seasonal mass balances from 2004 to 2010 for Batysh Sook Glacier located in the Kyrgyz Tien Shan. Conventional methods and a model-based extrapolation of the point measurements were used to obtain glacier-wide mass balances and to analyze glaciological measurements....

Université de Fribourg

Glacier monitoring and capacity building: important ingredients for sustainable mountain development

Nussbaumer, Samuel U. ; Hoelzle, Martin ; Hüsler, Fabia ; Huggel, Christian ; Salzmann, Nadine ; Zemp, Michael

In: Mountain Research and Development, 2017, vol. 37, no. 1, p. 141–152

Glacier observation data from major mountain regions of the world are key to improving our understanding of glacier changes: they deliver fundamental baseline information for climatological, hydrological, and hazard assessments. In many mountain ecosystems, as well as in the adjacent lowlands, glaciers play a crucial role in freshwater provision and regulation. This article first presents the...

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

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

Mass-balance reconstruction for Glacier No. 354, Tien Shan, from 2003 to 2014

Kronenberg, Marlene ; Barandun, Martina ; Hoelzle, Martin ; Huss, Matthias ; Farinotti, Daniel ; Azisov, Erlan ; Usubaliev, Ryskul ; Gafurov, Abror ; Petrakov, Dmitry ; Kääb, Andreas

In: Annals of Glaciology, 2016, vol. 57, no. 71, p. 92–102

This study presents a reconstruction of the seasonal mass balance of Glacier No. 354, located in the Akshiirak range, Kyrgyzstan, from 2003 to 2014. We use a distributed accumulation and temperature-index melt model driven by daily air temperature and precipitation from a nearby meteorological station. The model is calibrated with in situ measurements of the annual mass balance collected from...

Université de Fribourg

Semi-automated calibration method for modelling of mountain permafrost evolution in Switzerland

Marmy, Antoine ; Rajczak, Jan ; Delaloye, Reynald ; Hilbich, Christin ; Hoelzle, Martin ; Kotlarski, Sven ; Lambiel, Christophe ; Noetzli, Jeannette ; Phillips, Marcia ; Salzmann, Nadine ; Staub, Benno ; Hauck, Christian

In: The Cryosphere, 2016, vol. 10, no. 6, p. 2693–2719

Permafrost is a widespread phenomenon in mountainous regions of the world such as the European Alps. Many important topics such as the future evolution of permafrost related to climate change and the detection of permafrost related to potential natural hazards sites are of major concern to our society. Numerical permafrost models are the only tools which allow for the projection of the future...