Articles | Volume 5, issue 2
Earth Syst. Sci. Data, 5, 277–287, 2013
Earth Syst. Sci. Data, 5, 277–287, 2013

  30 Jul 2013

30 Jul 2013

Seasonal velocities of eight major marine-terminating outlet glaciers of the Greenland ice sheet from continuous in situ GPS instruments

A. P. Ahlstrøm1, S. B. Andersen1, M. L. Andersen1, H. Machguth1, F. M. Nick2,3, I. Joughin4, C. H. Reijmer3, R. S. W. van de Wal3, J. P. Merryman Boncori5, J. E. Box1,6, M. Citterio1, D. van As1, R. S. Fausto1, and A. Hubbard7 A. P. Ahlstrøm et al.
  • 1Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen, Denmark
  • 2Laboratoire de Glaciologie, Université libre de Bruxelles, Brussels, Belgium
  • 3Institute for Marine and Atmospheric research Utrecht, Utrecht University, Utrecht, the Netherlands
  • 4Applied Physics Laboratory, University of Washington, Seattle, USA
  • 5National Space Institute, Danish Technical University, Kgs. Lyngby, Denmark
  • 6Byrd Polar Research Center and Department of Geography, The Ohio State University, Columbus, USA
  • 7Institute of Geography & Earth Sciences, Aberystwyth University, Aberystwyth, UK

Abstract. We present 17 velocity records derived from in situ stand-alone single-frequency Global Positioning System (GPS) receivers placed on eight marine-terminating ice sheet outlet glaciers in South, West and North Greenland, covering varying parts of the period summer 2009 to summer 2012. Common to all the observed glacier velocity records is a pronounced seasonal variation, with an early melt season maximum generally followed by a rapid mid-melt season deceleration. The GPS-derived velocities are compared to velocities derived from radar satellite imagery over six of the glaciers to illustrate the potential of the GPS data for validation purposes. Three different velocity map products are evaluated, based on ALOS/PALSAR data, TerraSAR-X/Tandem-X data and an aggregate winter TerraSAR-X data set. The velocity maps derived from TerraSAR-X/Tandem-X data have a mean difference of 1.5% compared to the mean GPS velocity over the corresponding period, while velocity maps derived from ALOS/PALSAR data have a mean difference of 9.7%. The velocity maps derived from the aggregate winter TerraSAR-X data set have a mean difference of 9.5% to the corresponding GPS velocities. The data are available from the GEUS repository at doi:10.5280/GEUS000001.