Articles | Volume 11, issue 3
The Cryosphere, 11, 1501–1517, 2017
The Cryosphere, 11, 1501–1517, 2017

Research article 30 Jun 2017

Research article | 30 Jun 2017

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 M. Howat4, Guðfinna Aðalgeirsdóttir1, Tómas Jóhannesson3, and Alexander H. Jarosch1 Joaquín M. C. Belart et al.
  • 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, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Statistics in snow- and ice-free areas reveal similar vertical relative accuracy (<  0.5 m) with and without ground control points (GCPs), demonstrating the capability for measuring seasonal snow accumulation. The calculated winter (14 October 2014 to 22 May 2015) mass balance of Drangajökull was 3.33 ± 0.23 m w.e. (meter water equivalent), with ∼ 60 % of the accumulation occurring by February, which is in good agreement with nearby ground observations. On average, the repeated DEMs yield 22 % less elevation change than the length of eight winter snow cores due to (1) the time difference between in situ and satellite observations, (2) firn densification and (3) elevation changes due to ice dynamics. The contributions of these three factors were of similar magnitude. This study demonstrates that seasonal geodetic mass balance can, in many areas, be estimated from sub-meter resolution satellite stereo images.

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 is done by creating and comparing accurate digital elevation models. A glacier-wide geodetic mass balance of 3.33 ± 0.23 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.