How accurate are estimates of glacier ice thickness? Results from ITMIX, the Ice Thickness Models Intercomparison eXperiment
Daniel Farinotti1,2,Douglas J. Brinkerhoff3,Garry K. C. Clarke4,Johannes J. Fürst5,Holger Frey6,Prateek Gantayat7,Fabien Gillet-Chaulet8,Claire Girard9,Matthias Huss1,10,Paul W. Leclercq11,Andreas Linsbauer6,10,Horst Machguth6,10,Carlos Martin12,Fabien Maussion13,Mathieu Morlighem9,Cyrille Mosbeux8,Ankur Pandit14,Andrea Portmann2,Antoine Rabatel8,RAAJ Ramsankaran14,Thomas J. Reerink15,Olivier Sanchez8,Peter A. Stentoft16,Sangita Singh Kumari14,Ward J. J. van Pelt17,Brian Anderson18,Toby Benham19,Daniel Binder20,Julian A. Dowdeswell19,Andrea Fischer21,Kay Helfricht21,Stanislav Kutuzov22,Ivan Lavrentiev22,Robert McNabb3,11,G. Hilmar Gudmundsson12,Huilin Li23,and Liss M. Andreassen24Daniel Farinotti et al. Daniel Farinotti1,2,Douglas J. Brinkerhoff3,Garry K. C. Clarke4,Johannes J. Fürst5,Holger Frey6,Prateek Gantayat7,Fabien Gillet-Chaulet8,Claire Girard9,Matthias Huss1,10,Paul W. Leclercq11,Andreas Linsbauer6,10,Horst Machguth6,10,Carlos Martin12,Fabien Maussion13,Mathieu Morlighem9,Cyrille Mosbeux8,Ankur Pandit14,Andrea Portmann2,Antoine Rabatel8,RAAJ Ramsankaran14,Thomas J. Reerink15,Olivier Sanchez8,Peter A. Stentoft16,Sangita Singh Kumari14,Ward J. J. van Pelt17,Brian Anderson18,Toby Benham19,Daniel Binder20,Julian A. Dowdeswell19,Andrea Fischer21,Kay Helfricht21,Stanislav Kutuzov22,Ivan Lavrentiev22,Robert McNabb3,11,G. Hilmar Gudmundsson12,Huilin Li23,and Liss M. Andreassen24
1Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
2Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
3Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
4Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
5Institute of Geography, Friedrich Alexander University of Erlangen-Nuremberg (FAU), Erlangen, Germany
6Department of Geography, University of Zurich, Zurich, Switzerland
7Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
8Institut des Géosciences de l'Environnement (IGE), Université Grenoble Alpes, CNRS, IRD, Grenoble, France
9Department of Earth System Science, University of California Irvine, Irvine, CA, USA
10Department of Geosciences, University of Fribourg, Fribourg, Switzerland
11Department of Geosciences, University of Oslo, Oslo, Norway
12British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
13Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria
14Department of Civil Engineering, Indian Institute of Technology, Bombay, India
15Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands
16Arctic Technology Centre ARTEK, Technical University of Denmark, Kongens Lyngby, Denmark
17Department of Earth Sciences, Uppsala University, Uppsala, Sweden
18Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand
19Scott Polar Research Institute, University of Cambridge, Cambridge, UK
20Central Institute for Meteorology and Geodynamics (ZAMG), Vienna, Austria
21Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innsbruck, Austria
22Laboratory of Glaciology, Institute of Geography, Russian Academy of Science, Moscow, Russia
23State Key Laboratory of Cryospheric Sciences, Tian Shan Glaciological Station, CAREERI, CAS, Lanzhou, China
24Norwegian Water Resources and Energy Directorate (NVE), Oslo, Norway
1Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
2Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
3Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
4Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
5Institute of Geography, Friedrich Alexander University of Erlangen-Nuremberg (FAU), Erlangen, Germany
6Department of Geography, University of Zurich, Zurich, Switzerland
7Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
8Institut des Géosciences de l'Environnement (IGE), Université Grenoble Alpes, CNRS, IRD, Grenoble, France
9Department of Earth System Science, University of California Irvine, Irvine, CA, USA
10Department of Geosciences, University of Fribourg, Fribourg, Switzerland
11Department of Geosciences, University of Oslo, Oslo, Norway
12British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
13Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria
14Department of Civil Engineering, Indian Institute of Technology, Bombay, India
15Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands
16Arctic Technology Centre ARTEK, Technical University of Denmark, Kongens Lyngby, Denmark
17Department of Earth Sciences, Uppsala University, Uppsala, Sweden
18Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand
19Scott Polar Research Institute, University of Cambridge, Cambridge, UK
20Central Institute for Meteorology and Geodynamics (ZAMG), Vienna, Austria
21Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innsbruck, Austria
22Laboratory of Glaciology, Institute of Geography, Russian Academy of Science, Moscow, Russia
23State Key Laboratory of Cryospheric Sciences, Tian Shan Glaciological Station, CAREERI, CAS, Lanzhou, China
24Norwegian Water Resources and Energy Directorate (NVE), Oslo, Norway
Correspondence: Daniel Farinotti (daniel.farinotti@ethz.ch)
Received: 25 Oct 2016 – Discussion started: 29 Nov 2016 – Revised: 03 Mar 2017 – Accepted: 22 Mar 2017 – Published: 18 Apr 2017
Abstract. Knowledge of the ice thickness distribution of glaciers and ice caps is an important prerequisite for many glaciological and hydrological investigations. A wealth of approaches has recently been presented for inferring ice thickness from characteristics of the surface. With the Ice Thickness Models Intercomparison eXperiment (ITMIX) we performed the first coordinated assessment quantifying individual model performance. A set of 17 different models showed that individual ice thickness estimates can differ considerably – locally by a spread comparable to the observed thickness. Averaging the results of multiple models, however, significantly improved the results: on average over the 21 considered test cases, comparison against direct ice thickness measurements revealed deviations on the order of 10 ± 24 % of the mean ice thickness (1σ estimate). Models relying on multiple data sets – such as surface ice velocity fields, surface mass balance, or rates of ice thickness change – showed high sensitivity to input data quality. Together with the requirement of being able to handle large regions in an automated fashion, the capacity of better accounting for uncertainties in the input data will be a key for an improved next generation of ice thickness estimation approaches.
ITMIX – the Ice Thickness Models Intercomparison eXperiment – was the first coordinated performance assessment for models inferring glacier ice thickness from surface characteristics. Considering 17 different models and 21 different test cases, we show that although solutions of individual models can differ considerably, an ensemble average can yield uncertainties in the order of 10 ± 24 % the mean ice thickness. Ways forward for improving such estimates are sketched.
ITMIX – the Ice Thickness Models Intercomparison eXperiment – was the first coordinated...
