Scientific results

Because of weak inputs of nutrients in the surface mixed layer, chlorophyll concentration always remains low in the subtropical gyres. These weak inputs of nutrients are due to the downward Ekman pumping and to the deep nutricline. The now available decade of satellite sea colour data gives us the opportunity to follow the evolution of the chlorophyll concentration on these poorly-cloudy areas.

For several years, the CERSAT has been providing sea ice data and maps from various scatterometers (microwave radar) and radiometers onboard earth observation satellites (ERS-1, ERS-2, ADEOS-1, QuikSCAT, SSM/I, AMSR-E).

The scatterometer is initially designed to measure winds over ocean surface, but it can also be used to detect sea ice edge and sea ice type (first year, multi-year). Radiometer is commonly used for sea ice concentration. Using correlation technique between successive maps, sea ice drifts can be estimated from both of these sensors.

JASON-1 is a new franco-american altimeter launched in December 2001. Using the colocated datasets distributed at CERSAT, here is a first estimation by Pierre Queffeulou (IFREMER/CERSAT) of Jason data quality from comparisons with other altimeters as well as in-situ (buoys) measurements. This study focus on wind and significant wave height measurements provided by this instrument. They are inter-compared with similar observations by ERS-2 and GFO altimeters.

For several years the CERSAT has been providing sea ice maps derived from various scatterometers (microwave radar) on board earth observation satellites (ERS-1, ERS-2, ADEOS-1 or QuikSCAT). This instruments initially designed for measuring winds at the ocean surface allow to detect both the edge of the ice pack and the nature of the ice which it is made of (first-year, old ice, ...). A correlation analysis technique between successive maps is used to determine the movements animating this sea ice, mainly under the effect of the winds.