Sentinel-1 provides ice drift observations for Copernicus Marine Environment Monitoring Service (CMEMS)
Abstract
Sea ice drift information with an accuracy that allows also ice deformation (divergence, shear, vorticity) to be derived is being operationally generated in the Copernicus Marine Environment Monitoring Service (CMEMS).The method is based on 2-dimensional digital cross correlation where subsections of 2 consecutive images (typically 12-36h apart) are compared and the ice displacement defined as the shift in location of images 1 that maximizes the cross correlation with image 2. The method is also known as Maximum Cross Correlation or MCC.Implementation was carried out in the context of the PolarView project in 2007 when large volumes of ENVISAT ASAR images of the Polar regions became available during the International Polar Year. A dataset of daily ice drift vectors of the Polar Regions (North and South) is now available covering the time period from 2007 to the present time.In 2009 the processing became part of the GMES Marine Core Service MyOcean and when ENVISAT seized operation in 2012, this enabled a switch to daily RADARSAT-2 coverage of key regions in both hemispheres covered by the GMES Space Component Data Access (GSC-DA) grant.From October 2014, the data provision has switched to Sentinel-1 the source for SAR data, and the daily coverage of ice drift is now similar to what was reached with ENVISAT during the IPY. With the Launch of Sentinel-1B in 2016, daily coverage of most of the Arctic Ocean will become possible.Already today approximately 10.000 Sentinel-1A image pairs are matched every month in the processing system.The quality of the ice drift vectors are routinely verified against GPS locations of drift buoys and the RMS difference between the baseline product available through the Copernicus Marine Environment Monitoring Service data portal and GPS drifters is ~500 meters per day. A significant part of this RMS difference can be ascribed to the different nature of a point measurement and an area measurement.This accuracy is sufficient to support the generation of daily maps of ice divergence, shear and vorticity as the spatial derivatives of the ice drift field.The deformation fields are produced in the FP7 POLAR ICE project which develops methods for downstream distribution of ice related information to end-users in Polar Regions.The presentation will provide more details on the processing system and examples of the products and the POLAR ICE downstream service.
Info
Conference Abstract, 2016
UN SDG Classification
DK Main Research Area
Science/Technology
