DOI: 10.7280/d1595v
title: Annual Ice Velocity of the Greenland Ice Sheet (2001-2010)

description: We derive surface ice velocity using data from 16 satellite sensors
 deployed by 6 different space agencies. The list of sensors and the year
 that they were used are listed in the following (Table S1). The SAR data
 are processed from raw to single look complex using the GAMMA processor
 (www.gamma-rs.ch). All measurements rely on consecutive images where the
 ice displacement is estimated from tracking or interferometry (Joughin et
 al. 1998, Michel and Rignot 1999, Mouginot et al. 2012). Surface ice
 motion is detected using a speckle tracking algorithm for SAR instruments
 and feature tracking for Landsat. The cross-correlation program for both
 SAR and optical images is ampcor from the JPL/Caltech repeat orbit
 interferometry package (ROI_PAC). We assembled a composite ice velocity
 mosaic at 150 m posting using our entire speed database as described in
 Mouginot et al. 2017 (Fig. 1A). The ice velocity maps are also mosaicked
 in annual maps at 150 m posting, covering July, 1st to June, 30th of the
 following year, i.e. centered on January, 1st (12) because a majority of
 historic data were acquired in winter season, hence spanning two calendar
 years. We use Landsat-1&2/MSS images between 1972 and 1976 and
 combine image pairs up to 1 year apart to measure the
 displacement of surface features between images as described in Dehecq et
 al., 2015 or Mouginot et al. 2017. We use the 1978 2-m orthorectified
 aerial images to correct the geolocation of Landsat-1 and -2 images
 (Korsgaard et al., 2016). Between 1984 and 1991, we processed
 Landsat-4&5/TM image pairs acquired up to 1-year apart. Only few
 Landsat-4 and -5 images (~3%) needed geocoding refinement using the same
 1978 reference as used previously. Between 1991 and 1998, we process radar
 images from the European ERS-1/2, with a repeat cycle varying from 3 to 36
 days depending on the mission phase. Between 1999 and 2013, we use
 Landsat-7, ASTER, RADARSAT-1/2, ALOS/PALSAR, ENVISAT/ASAR to determine
 surface velocity (Joughin et al., 2010; Howat, I. 2017; Rignot &
 Mouginot, 2012). After 2013, we use Landsat-8, Sentinel-1a/b and
 RADARSAT-2 (Mouginot et al., 2017). All synthetic aperture radar (SAR)
 datasets are processed assuming surface parallel flow using the digital
 elevation model (DEM) from the Greenland Mapping Project (GIMP; Howat et
 al., 2014) and calibrated as described in Mouginot et al., 2012, 2017.
 Data were provided by the European Space Agency (ESA) the EU Copernicus
 program (through ESA), the Canadian Space Agency (CSA), the Japan
 Aerospace Exploration Agency (JAXA), the Agenzia Spaziale Italiana (ASI),
 the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) and the National
 Aeronautics and Space Administration (NASA). SAR data acquisition were
 coordinated by the Polar Space Task Group (PSTG). References: Dehecq, A,
 Gourmelen, N, Trouve, E (2015). Deriving large-scale glacier velocities
 from a complete satellite archive: Application to the
 Pamir-Karakoram-Himalaya. Remote Sensing of Environment, 162, 55–66. Howat
 IM, Negrete A, Smith BE (2014) The greenland ice mapping project (gimp)
 land classification and surface elevation data sets. The Cryosphere
 8(4):1509–1518. Howat, I (2017). MEaSUREs Greenland Ice Velocity: Selected
 Glacier Site Velocity Maps from Optical Images, Version 2. Boulder,
 Colorado USA. NASA National Snow and Ice Data Center Distributed Active
 Archive Center. Joughin, I., B. Smith, I. Howat, T. Scambos, and T. Moon.
 (2010). Greenland Flow Variability from Ice-Sheet-Wide Velocity Mapping,
 J. of Glac.. 56. 415-430. Joughin IR, Kwok R, Fahnestock MA (1998)
 Interferometric estimation of three dimensional ice-flow using ascending
 and descending passes. IEEE Trans. Geosci. Remote Sens. 36(1):25–37.
 Joughin, I, Smith S, Howat I, and Scambos T (2015). MEaSUREs Greenland Ice
 Sheet Velocity Map from InSAR Data, Version 2. [Indicate subset used].
 Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed
 Active Archive Center. Michel R, Rignot E (1999) Flow of Glaciar Moreno,
 Argentina, from repeat-pass Shuttle Imaging Radar images: comparison of
 the phase correlation method with radar interferometry. J. Glaciol.
 45(149):93–100. Mouginot J, Scheuchl B, Rignot E (2012) Mapping of ice
 motion in Antarctica using synthetic-aperture radar data. Remote Sens.
 4(12):2753–2767. Mouginot J, Rignot E, Scheuchl B, Millan R (2017)
 Comprehensive annual ice sheet velocity mapping using landsat-8,
 sentinel-1, and radarsat-2 data. Remote Sensing 9(4). Rignot E, Mouginot J
 (2012) Ice flow in Greenland for the International Polar Year 2008-2009.
 Geophys. Res. Lett. 39, L11501:1–7.