A. Carlstrom et Lmh. Ulander, C-BAND BACKSCATTER SIGNATURES OF OLD SEA-ICE IN THE CENTRAL ARCTIC DURING FREEZE-UP, IEEE transactions on geoscience and remote sensing, 31(4), 1993, pp. 819-829
Radar backscatter signatures of old sea ice in the central Arctic have
been measured and analyzed. A ship-mounted scatterometer was used to
acquire backscattering coefficients at 5.4 GHz in the four linear Pola
rization states and at incidence angles between 20 degrees and 60 degr
ees. Detailed in situ characterizations of the snow and iee were also
made to enable comparison with theoretical backscatter models. Freeze-
up conditions were prevalent during the experiment period with air tem
peratures a few degrees below the freezing point and decreasing. The a
verage backscattering coefficient mas found to increase when the tempe
rature of the ice surface layer decreased. The semiempirical backscatt
er model is used to evaluate the measurements and shows that the backs
catter increase is due to an increasing penetration depth causing the
volume scattering to increase. In the paper, model predictions also sh
ow that both surface and volume scattering contribute significantly fo
r the incidence angles of the ERS-1 SAR, i.e., 20 degrees to 26 degree
s. At these incidence angles, the dominating scattering mechanism chan
ges from surface to volume scattering as the ice surface temperature d
ecreases during freeze-up.