DOI: 10.15146/zf0j-5m50
title: Grounding line of Denman Glacier, East Antarctica from satellite radar interferometry

description: Grounding line, elevation changes, and melt rates maps of Denman Glacier,
 East Antarctica. Using satellite radar interferometry from the
 COSMO-SkyMed mission we map the grounding line of Denman Glacier, East
 Antarctica. We complement these data with some historical interferometric
 radar acquisition from the European satellite ERS-1/2. We present new maps
 of elevation changes on the grounded and floating portions of Denman
 Glacier obtained by temporally differencing TanDEM-X Digital Elevation
 Models.
description: To map the grounding line of Denman Glacier, we form SAR
 interferograms with a one day time interval by coherently combining SAR
 acquisitions from ERS-1/2 satellites in 1996 and from the Agenzia Spaziale
 Italiana (ASI) COSMO-SkyMed (CSK) mission between 2016 and 2018. We
 multi-look each interferogram with a 8x8 averaging window and remove the
 topographic signal affecting each interferometric acquisition with a
 TanDEM-X (TDX) at 30 m spacing. We form 29 CSK Differential Interferogram
 (DInSAR) (i.e. difference between two SAR interferograms) to reveal the
 vertical motion of ice in response to changes in oceanic tides.
 We generate a time series of Digital Elevation Model at 12 m
 spacing and meter-scale vertical precision using SAR bistatic acquisition
 from the TDX mission. The processing chain includes: a) spaceborne
 monostatic TerraSAR-X processing; b) bistatic TDX processing; c)
 interferometric combination of images; d) phase unwrapping; e)
 phase-to-height conversion; f) geocoding to a latitude/longitude
 grid. We differentiate temporally separated TDX DEMs to
 generate elevation changes map on grounded ice and ocean-induced melt
 rates maps on floating ice. We smooth elevation changes maps (dh/dt) using
 a 15x15 pixels moving average window to obatain dh/dt maps at 1.5 km
 spacing. On floating ice, we differentiate TDX DEMs by
 tracking ice parcel with time and correcting for ice flow divergence. We
 use a chip size of 30x30 pixels with steps of 16 pixels in both horizontal
 and vertical directions and smooth the results with a 15x15 moving average
 window to obtain ocean-induced melt rate maps at 1.5 km spacing.
description: The grounding line  data are formatted in an ESRI shapefile
 format storing nontopological and attribute information (e.g. acquisition
 dates, orbit numbers) for the spatial features in the dataset. The title
 of each file carries information on the acquisition dates of the doub;e
 difference used to generate the grounding line shapefile.
 The DInSAR interferograms are stored in a GeoTiff format. The
 title of each file carries information on the acquisition dates of the SAR
 images used to generate the DInSAR Interferogram. The elevation change
 rates maps and the ocean-induced melt rates are similarly stored in
 GeoTiff files. Spatial
 coverage The dataset spans the area covered
 by Denman Glacier,  East Antarctica. All the data is in polar
 stereographic projection with true scale at 71S. As a
 condition to use the data, please cite the following
 publication, Brancato, V., Rignot, E., Milillo, P.,
 Morlighem, M., An, L., Scheuchl, B., ..., Prats-Iraola, "Grounding
 line retreat of Denman Glacier, East Antarctica, measured with
 COSMO-SkyMed radar interferometry", Geophys. Res. Lett., in
 press