How accurate are estimates of glacier ice thickness?
Results from ITMIX, the Ice Thickness Models Intercomparison
eXperiment

Farinotti, Daniel; Brinkerhoff, Douglas; Fürst, Johannes J.; Frey, Holger; Gantayat, Prateek; Gillet-Chaulet, Fabien; Girard, Claire; Huss, Matthias; Leclercq, Paul W.; Linsbauer, Andreas; Machguth, Horst; Martín, Carlos; Maussion, Fabien; Morlighem, Mathieu; Mosbeux, Cyrille; Pandit, Ankur; Portmann, Andrea; Rabatel, Antoine; Ramsankaran, Raaj; Reerink, Thomas; Sanchez, Olivier; Stentoft, Peter Alexander; Kumari, Sangita; Pelt, Ward van; Anderson, B. J.; Benham, Toby; Binder, Daniel; Dowdeswell, Julian A.; Fischer, Andrea; Kutuzov, Stanislav; Lavrentiev, Ivan; McNabb, Robert; Gudmundsson, G. Hilmar; Li, Huilin; Andreassen, Liss M.

doi:10.5194/tc-2016-250

Cited by 5 publications

(5 citation statements)

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“…This model applies a constant shear stress approximation following [29] and calculates ice depth from surface slope taking into account effects of elevation range on mass turn-over and interpolating between constructed branch lines for individual glaciers. Within the general uncertainty range of distributed ice-thickness estimates, the predictive quality of the approach is equal to more complex methods [30]. Major advantages of GlabTop are its simplicity, transparency, robustness (no tuning necessary), easily accessible input information, and rapid calculation.…”

Section: Methodsmentioning

confidence: 99%

Compiling an Inventory of Glacier-Bed Overdeepenings and Potential New Lakes in De-Glaciating Areas of the Peruvian Andes: Approach, First Results, and Perspectives for Adaptation to Climate Change

Colonia

Torres

Haeberli

et al. 2017

Water

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Global warming causes rapid shrinking of mountain glaciers. New lakes can, thus, form in the future where overdeepenings in the beds of still-existing glaciers are becoming exposed. Such new lakes can be amplifiers of natural hazards to downstream populations, but also constitute tourist attractions, offer new potential for hydropower, and may be of interest for water management. Identification of sites where future lakes will possibly form is, therefore, an essential step to initiate early planning of measures for risk reduction and sustainable use as part of adaptation strategies with respect to impacts from climate change. In order to establish a corresponding knowledge base, a systematic inventory of glacier-bed overdeepenings and possible future lakes was compiled for the still glacierized parts of the Peruvian Andes using the 2003-2010 glacier outlines from the national glacier inventory and the SRTM DEM from the year 2000. The resulting inventory contains 201 sites with overdeepened glacier beds >1 ha (10 4 m 2 ) where notable future lakes could form, representing a total volume of about 260 million m 3 . A rough classification was assigned for the most likely formation time of the possible new lakes. Such inventory information sets the stage for analyzing sustainable use and hazard/risk for specific basins or regions.

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Section: Methodsmentioning

confidence: 99%

Compiling an Inventory of Glacier-Bed Overdeepenings and Potential New Lakes in De-Glaciating Areas of the Peruvian Andes: Approach, First Results, and Perspectives for Adaptation to Climate Change

Colonia

Torres

Haeberli

et al. 2017

Water

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“…This normally comprises the glacier outline and the surface topography. In the "Ice Thickness Models Intercomparison eXperiment" (ITMIX; Farinotti et al, 2016), two types of reconstruction approaches rely exclusively on this geometric information. The first type stems from a perfect plasticity assumption, relating ice thicknesses to a glacier-specific yields stress, which itself is inferred from the elevation range of the glacier (Linsbauer et al, 2012;Frey et al, 2014;Carrivick et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

Fürst¹,

Gillet-Chaulet²,

Benham³

et al. 2017

Preprint

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Abstract. The basal topography is largely unknown beneath most glaciers and ice caps and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach performs well for a variety of test geometries with abundant thickness measurements including marine- and land-terminating glaciers as well as a 2400 km2 ice cap on Svalbard. Input requirements for the first step are comparable to other approaches that have already been applied world-wide. In the first step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation. In a second step, the thickness reconstruction is improved along fast-flowing glacier trunks on the basis of velocity observations. In both steps, thickness measurements are assimilated as internal boundary conditions. Each thickness field is presented together with a map of error estimates which stem from a formal propagation of input uncertainties. These estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. The error-estimate map also highlights key regions for future thickness surveys as well as a preference for across-flow acquisition. Withholding parts of the thickness measurements indicates that error estimates show a tendency to overestimate actual mismatch values. For very sparse or non-existent thickness information, our reconstruction approach indicates that we have to accept an average uncertainty of at least 25 % in the reconstructed thickness field. For Vestfonna, previous ice volume estimates have to be corrected upward by 22 %. We also find that a 12 % area fraction of the ice cap are in fact grounded below sea-level as compared to the previous 5 %-estimate.

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“…They are process based [58] and are independent from uncertain precipitation records. Their spatial resolution is higher than that of large-scale satellite approaches, and the combination of both seems beneficial.…”

Section: Glacier Evolution and Runoff Contributionmentioning

confidence: 99%

“…Both studies make use of remote sensing approaches in absence of a ground-based glacier monitoring. Here, we compare those satellite-based approaches to the GlabTop-based results, because glacier thickness modeling can have substantial uncertainties [58].…”

Section: Volumetric Glacier Changementioning

confidence: 99%

Bridging Glaciological and Hydrological Trends in the Pamir Mountains, Central Asia

Knoche

Merz

Lindner

et al. 2017

Water

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How accurate are estimates of glacier ice thickness? Results from ITMIX, the Ice Thickness Models Intercomparison eXperiment

Cited by 5 publications

References 0 publications

Compiling an Inventory of Glacier-Bed Overdeepenings and Potential New Lakes in De-Glaciating Areas of the Peruvian Andes: Approach, First Results, and Perspectives for Adaptation to Climate Change

Compiling an Inventory of Glacier-Bed Overdeepenings and Potential New Lakes in De-Glaciating Areas of the Peruvian Andes: Approach, First Results, and Perspectives for Adaptation to Climate Change

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

Bridging Glaciological and Hydrological Trends in the Pamir Mountains, Central Asia

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