Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-241
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Nov 2016
Review status
A revision of this discussion paper is under review for the journal The Cryosphere (TC).
Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images
Joaquín M. C. Belart1,2, Etienne Berthier2, Eyjólfur Magnússon1, Leif S. Anderson1, Finnur Pálsson1, Thorsteinn Thorsteinsson3, Ian Howat4, Guðfinna Aðalgeirsdóttir1, Tómas Jóhannesson3, and Alexander H. Jarosch1 1Institute of Earth Sciences, University of Iceland, Askja, Reykjavík, Iceland
2Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, Centre National de la Recherche Scientifique (LEGOS – CNRS), Université de Toulouse, Toulouse, France
3Icelandic Meteorological Office, Reykjavík, Iceland
4School of Earth Sciences and Byrd Polar and Climate Research Center, Ohio State University, Columbus, USA
Abstract. Sub-meter resolution satellite stereo images allow the generation of high resolution, accurate digital elevation models (DEMs). Repeated acquisitions of stereo images from Pléiades, in October 2014 and May 2015, and from WorldView2 (WV2), in February 2015, over Drangajökull ice cap (NW-Iceland) are used to estimate the geodetic glacier-wide mass balance on sub-annual time scales. Relative adjustment of the DEMs is performed with and without a pre-existing lidar DEM as source of ground control points (GCPs), and resulting statistics in snow-free and ice-free areas reveal similar vertical accuracy < 0.5 m for both methods. The estimated accuracy of the average elevation change from October to May, without using lidar GCPs, was 0.22 m, showing the capabilities of the satellites for measuring snow accumulation in a seasonal time span without external data. The winter mass balance of Drangajökull is Bw = 3.20 ± 0.21 m w.e. during October–May, and ~ 60 % of the accumulation occurred during October–February, a percentage in good agreement with the precipitation record at a nearby meteorological station. The elevation change from October to May was compared with winter snow thickness measured at 8 locations in June 2015. Winter snow of 6.5 m was measured in the cores on average while the DEM difference shows average elevation change of 5.1 m at the same locations. This systematic difference is explained by (1) difference in time between in situ and satellite observations, (2) firn compaction and (3) elevation change due to ice dynamics. This study demonstrates that seasonal geodetic mass balance can in many areas be measured from sub-meter resolution satellite stereo images, as a complement or even replacement of in situ measurements.

Citation: Belart, J. M. C., Berthier, E., Magnússon, E., Anderson, L. S., Pálsson, F., Thorsteinsson, T., Howat, I., Aðalgeirsdóttir, G., Jóhannesson, T., and Jarosch, A. H.: Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images, The Cryosphere Discuss., doi:10.5194/tc-2016-241, in review, 2016.
Joaquín M. C. Belart et al.
Joaquín M. C. Belart et al.
Joaquín M. C. Belart et al.

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Short summary
Sub-meter satellite stereo images (Pléiades and WorldView2) are used to accurately measure snow accumulation and winter mass balance of Drangajökull ice cap. This done by creating and comparing accurate digital elevation models. A glacier-wide geodetic mass balance of 3.20 ± 0.21 m w.e. is derived between October 2014 and May 2015. This method could be easily transposable to remote glaciated areas where seasonal mass balance measurements (especially winter accumulation) are lacking.
Sub-meter satellite stereo images (Pléiades and WorldView2) are used to accurately measure snow...
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