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Université de Fribourg

Robust climate scenarios for sites with sparse observations: a two-step bias correction approach

Rajczak, Jan ; Kotlarski, Sven ; Salzmann, Nadine ; Schär, Christoph

In: International Journal of Climatology, 2016, vol. 36, no. 3, p. 1226–1243

Observed and projected climatic changes demand for robust assessments of climate impacts on various environmental and anthropogenic systems. Empirical-statistical downscaling (ESD) methods coupled to output from climate model projections are promising tools to assess impacts at regional to local scale. ESD methods correct for common model deficiencies in accuracy (e.g. model biases) and scale...

Université de Fribourg

Climate trends and glacier retreat in the Cordillera Blanca, Peru, revisited

Schauwecker, S. ; Rohrer, M. ; Acuña, D. ; Cochachin, A. ; Dávila, L. ; Frey, H. ; Giráldez, C. ; Gómez, J. ; Huggel, C. ; Jacques-Coper, M. ; Loarte, E. ; Salzmann, Nadine ; Vuille, M.

In: Global and Planetary Change, 2014, vol. 119, p. 85–97

The total glacial area of the Cordillera Blanca, Peru, has shrunk by more than 30% in the period of 1930 to the present with a marked glacier retreat also in the recent decades. The aim of this paper is to assess local air temperature and precipitation changes in the Cordillera Blanca and to discuss how these variables could have affected the observed glacier retreat between the 1980s and...

Université de Fribourg

Li/Mg systematics in scleractinian corals: Calibration of the thermometer

Montagna, Paolo ; McCulloch, Malcolm ; Douville, Eric ; Correa, Matthias López ; Trotter, Julie ; Rodolfo-Metalpa, Riccardo ; Dissard, Delphine ; Ferrier-Pagès, Christine ; Frank, Norbert ; Freiwald, André ; Goldstein, Steve ; Mazzoli, Claudio ; Reynaud, Stephanie ; Rüggeberg, Andres ; Russo, Simone ; Taviani, Marco

In: Geochimica et Cosmochimica Acta, 2014, vol. 132, p. 288–310

We show that the Li/Mg systematics of a large suite of aragonitic coral skeletons, representing a wide range of species inhabiting disparate environments, provides a robust proxy for ambient seawater temperature. The corals encompass both zooxanthellate and azooxanthellate species (Acropora sp., Porites sp., Cladocora caespitosa, Lophelia pertusa, Madrepora...

Université de Fribourg

Simulating high-latitude permafrost regions by the JSBACH terrestrial ecosystem model

Ekici, A. ; Beer, C. ; Hagemann, S. ; Boike, J. ; Langer, M. ; Hauck, Christian

In: Geoscientific Model Development, 2014, vol. 7, no. 2, p. 631–647

The current version of JSBACH incorporates phenomena specific to high latitudes: freeze/thaw processes, coupling thermal and hydrological processes in a layered soil scheme, defining a multilayer snow representation and an insulating moss cover. Evaluations using comprehensive Arctic data sets show comparable results at the site, basin, continental and circumarctic scales. Such comparisons...

Université de Fribourg

Modeled sensitivity of two alpine permafrost sites to RCM-based climate scenarios

Scherler, Martin ; Hauck, Christian ; Hoelzle, Martin ; Salzmann, Nadine

In: Journal of Geophysical Research: Earth Surface, 2013, vol. 18, no. 2, p. 780–794

Climate change as projected by contemporary general circulation models (GCMs) and regional climate models (RCMs) will have a great impact on high latitude and high mountain permafrost. A process-based one-dimensional permafrost model is used to evaluate the sensitivity of two characteristic alpine permafrost sites to changes in climate for a 110 year time period starting 1991 and ending 2100...

Université de Fribourg

Extrapolating glacier mass balance to the mountain range scale: the European Alps 1900–2100

Huss, Matthias

In: The Cryosphere Discuss., 2012, vol. 6, p. 1117-1156

This study addresses the extrapolation of single glacier mass balance measurements to the mountain range scale and aims at deriving time series of area-averaged mass balance and ice volume change for all glaciers in the European Alps for the period 1900–2100. Long-term mass balance series for 50 Swiss glaciers based on a combination of field data and modelling, and WGMS data for glaciers in...

Université de Fribourg

Potential climatic transitions with profound impact on Europe: review of the current state of six ‘tipping elements of the climate system’

Levermann, Anders ; Bamber, Jonathan L. ; Drijfhout, Sybren ; Ganopolski, Andrey ; Haeberli, Winfried ; Harris, Neil R. P. ; Huss, Matthias ; Krüger, Kirstin ; Lenton, Timothy M. ; Lindsay, Ronald W. ; Notz, Dirk ; Wadhams, Peter ; Weber, Susanne

In: Climatic Change, 2011, vol. 110, no. 3-4, p. 845-878

We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field....

Université de Fribourg

Degrading mountain permafrost in southern Norway: spatial and temporal variability of mean ground temperatures, 1999–2009

Isaksen, Ketil ; Ødegård, Rune Strand ; Etzelmüller, Bernd ; Hilbich, Christin ; Hauck, Christian ; Farbrot, Herman ; Eiken, Trond ; Hygen, Hans Olav ; Hipp, Tobias Florian

In: Permafrost and Periglacial Processes, 2011, vol. 22, no. 2, p. 361–377

A ten-year record (1999–2009) of annual mean ground surface temperatures (MGSTs) and mean ground temperatures (MGTs) was analysed for 16 monitoring sites in Jotunheimen and on Dovrefjell, southern Norway. Warming has occurred at sites with cold permafrost, marginal permafrost and deep seasonal frost. Ongoing permafrost degradation is suggested both by direct temperature monitoring and indirect...

Université de Fribourg

Airborne in-situ investigations of the Eyjafjallajökull volcanic ash plume on Iceland and over north-western Germany with light aircrafts and optical particle counters

Weber, Klaus ; Eliasson, J. ; Vogel, A. ; Fischer, C. ; Pohl, T. ; Haren, G. van ; Meier, M. ; Grobéty, Bernard ; Dahmann, D.

In: Atmospheric Environment, 2011, vol. 48, p. 9-21

During the time period of the eruption of the Icelandic volcano Eyjafjallajökull in April/May 2010 the Duesseldorf University of Applied Sciences has performed 14 research flights in situations with and without the volcanic ash plume over Germany. In parallel to the research flights in Germany three measurement flights have been performed by the University of Iceland in May 2010 over the western...

Université de Fribourg

A new model for estimating subsurface ice content based on combined electrical and seismic data sets

Hauck, Christian ; Böttcher, Michael E. ; Maurer, H.

In: The Cryosphere, 2011, vol. 5, p. 453–468

Detailed knowledge of the material properties and internal structures of frozen ground is one of the prerequisites in many permafrost studies. In the absence of direct evidence, such as in-situ borehole measurements, geophysical methods are an increasingly interesting option for obtaining subsurface information on various spatial and temporal scales. The indirect nature of geophysical soundings...