Abstract :
For the cold seasons 1992-93 and 1996-97, when extensive multiyear ice coverages were observed in the Arctic Ocean, the active microwave signatures of multiyear ice have been analysed and compared to the brightness temperatures and the multiyear ice concentration maps derived from the SSM/I. Two ways are explored for using the backscatter data obtained by the AMI-WIND, aboard ERS, and NSCAT aboard ADEOS. Firstly, the stability of the backscatter data in time is used to constitute pairs of tie points between successive images which, added to buoy positions, are at the origin of a series of interpolated ice displacement fields calculated for 8 weeks periods. Applied to the multiyear ice maps deduced from the brightness temperatures of the SSM/I at the beginning of December 1992 and 1996, these motion fields give virtual maps of the displaced multiyear ice concentration which can be compared to really calculated maps. Secondly, the backscatter data are used to isolate homogeneous areas of highly reflective ice which appear to correspond to low estimated concentrations of multiyear ice. Though the author cannot, by using backscatter data only, know the true multiyear ice concentrations, it is possible to suppose a possible source of error, due to the particular emissivities of the ice surface, in the SSM/I evaluations
Keywords :
backscatter; oceanographic regions; oceanographic techniques; radar cross-sections; radiometry; remote sensing; remote sensing by radar; sea ice; spaceborne radar; AD 1992; AD 1993; AD 1996; AD 1997; Arctic Ocean; SSM/I; active microwave signature; backscatter; brightness temperature; ice displacement; ice motion; measurement technique; microwave emissivity; microwave radiometry; multiyear ice concentration change; ocean; radar remote sensing; radar scattering; radar scatterometry; scatterometer; sea ice; season; spaceborne radar; tie point; winter; Arctic; Backscatter; Brightness temperature; Ice surface; NASA; Ocean temperature; Pixel; Polarization; Radar measurements; Stability;