Ice volume and subglacial topography for western Canadian glaciers from mass balance fields, thinning rates, and a bed stress model

• Published in: Journal of Climate
• Main Authors: Clarke, G. K. C., Anslow, F., Jarosch, A., Radic, V., Menounos, Brian, Bolch, Tobias, Berthier, Etienne
• Other Authors: Earth and Ocean Sciences (EOS), University of British Columbia (UBC), Pacific Climate Impacts Consortium, University of Victoria Canada (UVIC), University of Innsbruck, Geography Program and Natural Resources Environmental Studies Institute (UNBC), University of Northern British Columbia Prince George (UNBC), Instituts für Kartographie Dresden (Institute for Cartography), Technische Universität Dresden = Dresden University of Technology (TU Dresden), Universität Zürich Zürich (UZH), GLACIO LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Canada; glacier*
• Online Access: https://hal.archives-ouvertes.fr/hal-00846330; https://hal.archives-ouvertes.fr/hal-00846330/document; https://hal.archives-ouvertes.fr/hal-00846330/file/Clarke_et_al_JC_2013.pdf; https://doi.org/10.1175/JCLI-D-12-00513.1

International audience A method is described to estimate the thickness of glacier ice using information derived from the measured ice extent, surface topography, surface mass balance, and rate of thinning or thickening of the ice column. Shear stress beneath an ice column is assumed to be simply related to ice thickness and surface slope, as for an inclined slab, but this calculation is cast as a linear optimization problem so that a smoothness regularization can be applied. Assignment of bed stress is based on the flow law for ice and a mass balance calculation but must be preceded by delineation of the ice flow drainage basin. Validation of the method is accomplished by comparing thickness estimates to the known thickness generated by a numerical ice dynamics model. Once validated, the method is used to estimate the subglacial topography for all glaciers in western Canada that lie south of 60°N. Adding the present ice volume of each glacier gives the estimated total volume as 2320 km^3, equivalent to 5.8 mm of sea level rise. Taking the glaciated area as 26 590 km² gives the average glacier thickness as 87.2 m. A detailed error analysis indicates that systematic errors are likely to increase the estimated sea level rise and when random errors are included the combined result is 6.3 ± 0.6 mm or, expressed as ice volume, 2530 ± 220 km^3.