The on-going studies of sea-ice use satellite data from both passive (SMMR, SSM/I, ATSR/M) and active (scatterometers such as ERS/AMI-Wind of ERS-1 and ERS-2, ADEOS/NSCAT or QuikSCAT/SeaWinds) microwave sensors, which are complementary. The scientists of CERSAT use these sensors to :
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Figure 1 : Comparison of buoys and Merged drifts for 3 day-lag, winters 1999-2004. Colors are probability expressed in logarithm scale.
Satellites enable daily and global coverage of the polar oceans, providing an unique monitoring capability of sea ice dynamics over Arctic and Antarctic. Available geophysical parameters include ice concentration, extent, type and sea ice drift.
Backscatter map from SeaWinds/QuikSCAT and brightness temperature maps from Special Sensor Microwave Imager (SSM/I) are available at a pixel resolution of 12,5 km from which ice drift can be estimated for each sensor. Since 1999, IFREMER makes available a 'Merged' sea ice drift data set based on the combination of these drifts at 3 and 6-day lags at the grid resolution of 62,5 km. It has been demonstrated that combining these drifts increases the number of valid vectors.In this paper, the validation of this Merged product is presented in comparison with drifting buoys of the International Arctic Buoy Programme (IABP) over five winters (1999-2004), enabling an estimation of drift accuracy as a function of drift speed.
In the second part, the accuracy of the Advanced Microwave Scanning Radiometer (AMSR-E) drift products based on 89 GHz brightness temperature maps at 6,25 km pixel resolution is assessed. Drift data are compared with the buoys positions and with the Merged product during the 2002-2003 winter. AMSR-E provides a better vector accuracy compared with that of the Merged product because of its enhanced ground resolution but the information is available only during the cold season.
Radar backscatter of sea-ice
Monitoring Sea Ice using Scatterometers of the European Remote-Sensing Satellites