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The behaviour of southern elephant seals from Kerguelen Island (4950′S, 7030′E) was investigated in relation to the oceanographic regions of the Southern Ocean. The oceanographic and the seal behaviour data, including location and diving activity, were collected using a new generation of satellite-relayed devices measuring and transmitting pressure, temperature, and salinity along with locations. Dive duration, maximum diving depth, time spent at the bottom of the dives, and shape of dive profiles were compared between male and female seals, and were related to the oceanographic characteristics of areas prospected by the seals. Most animals travelled to the Antarctic shelf. However, during winter, adult females travelled away from the continent, remained and foraged within the marginal sea-ice zone, while juvenile males remained within the pack ice to forage mainly on the Antarctic shelf. Therefore, as the ice expanded females appeared to shift from benthic to pelagic foraging farther north, while males continued to forage almost exclusively benthically on the continental shelf. This difference is likely related to the different energetic requirements between the two sexes, but also may be related to pregnant females having to return to Kerguelen in early spring in order to give birth and successfully raise their pups, while males can remain in the ice. Our results show an important link between elephant seals and Antarctic sea ice and suggest that changes in seaice conditions could strongly affect the behaviour of this species.

Satellites enable daily and global coverage of the polar oceans and provide a unique monitoring capability of sea ice dynamics. Sea ice drift maps can be estimated in Arctic from several satellite sensors, particularly from scatterometers and radiometers. This study presents the benefits of combining single drift fields at the same resolution into a "merged" field, built at three-and six-day lags during winters with a 62.5-km resolution. It is shown that combining these drift fields not only increases the reliability of the displacement estimation and the number of estimated vectors to almost a full ice covered area but also expands the time period over which these estimations are reliable from freeze until the melt onset. The autumn-winter-spring sea ice drift fields presented here are systematically produced at

Abstract. C band and Ku band Arctic Ocean sea ice backscatter maps at 40 ø incidence angle, produced from the ERS 2 active microwave instrument operating in scatterometer mode and Advanced Earth Observing System NASA scatterometers, respectively, are presented and compared. The noise level on these maps is estimated from the comparison of successive maps and is found comparable, although larger at C band than at Ku band.In both cases the relative noise level increases as backscatter level decreases. Backscatter shows a greater dynamic range at Ku band than at C band, going from first-year to multiyear ice; moreover, the Ku band to C band backscatter ratio varies considerably as a function of sea ice type. Surface thawing, in June, leads to a brutal decrease in backscatter in both frequency bands, as well as in the Ku band to C band ratio. The study of the time evolution of backscatter over five different regions of the Arctic Ocean demonstrates the influence of both advection and local evolution on this parameter.