Satellite-derived high-resolution sea-ice motion, 2007-2011 - Envisat Satellite Data

• Other Authors: AADC (originator), AU/AADC > Australian Antarctic Data Centre, Australia (resourceProvider)
• Format: Dataset
• Language: unknown
• Published: Australian Ocean Data Network
• Subjects: oceans; SEA ICE MOTION; EARTH SCIENCE; SEA ICE; IMAGE CROSSCORRELATION; SAR > Synthetic Aperture Radar; ENVISAT > Environmental Satellite; ACE/CRC; AMD/AU; AMD; CEOS; GEOGRAPHIC REGION > POLAR; OCEAN > SOUTHERN OCEAN; CONTINENT > ANTARCTICA; Antarctic; Southern Ocean; Austral; Asar; Giles; Antarc*; Antarctica; Sea ice
• Online Access: https://researchdata.edu.au/satellite-derived-high-envisat-satellite/1668615; https://data.aad.gov.au/metadata/records/AAS_4301_Envisat_sea_ice_motion; https://data.aad.gov.au/eds/5207/download; https://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=AAS_4301_Envisat_sea_ice_motion; https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=4301

The geolocation accuracy of the relevant Envisat ASAR products have an absolute error of up to 750 m (10 pixels) due to inaccuracies in the positional specifications in the SAR image headers. However, as the sea-ice motion applies a differencing technique, the absolute errors offset each other and derived ice displacement are in the order of 1.5pixels width or 115m. Envisat was was launched on 01/03/2002, by ESA and operated until 08/04/2012. It provided suitable imagery for the austral winters (May - November) of 2007 to 2011. Envisat caried a C-band (5.33 GHz; wavelength ∼ 5.6 cm) Advanced Synthetic Aperture Radar [ASAR], capable to acquire data in multiple modes (image, alternating polarization, wave, ScanSAR (wide swath), and ScanSAR (global monitoring)) at various incidence angles and in several polarisations. Of ASAR's five distinct measurement modes, the following two modes may be used to derive sea-ice motion from overlapping images in our project: 1. ASAR Wide Swath Mode -- 400 km by 400 km wide swath image. Spatial resolution of approximately 150 m by 150 m for nominal product. VV or HH polarization. 2. ASAR Global Monitoring Mode -- Spatial resolution of approximately 1000 m in azimuth by 1000 m in range for nominal product. Up to a full orbit of coverage. HH or VV polarization. For further detail, see ESA's Copernicus web portal. Sea-ice motion is derived from suitable SAR image pairs with sufficient spatial overlap but relatively short time separation, i.e. ideally 6days or less. Image-crosscorrelation analysis is employed to identify displacement vectors within the image pair. The underlying processing and analysis is part of the (mostly) automated IMCORR [IMageCORRelation] Processing, Analysis and Display System [IPADS]. This study uses C-band (HH polarisation) ASAR scenes, with an image pixel size of 75 m across a 405 km swath. -- For further information see Giles et al., Semi-automated feature-tracking of East Antarctic sea ice from Envisat ASAR imagery, Remote Sensing of Environment, 115, 2267-2276, 2011. Acknowledgement: All Envisat ASAR data are courtesy of the European Space Agency, and were obtained under agreement with ESA. The International Space Science Institute (ISSI), Bern, Switzerland, is acknowledged for supporting this study via Projects 137 and 169. The purpose of this dataset was to create a NetCDF-format database of high-resolution(:SAR) Antarctic sea-ice motion vectors.