Observation systems

The ocean is certainly, at the earth's surface, the system that is most difficult to observe. For thisn it has long remained mostly unknown. It is thus not surprizing that the recent development of the ocean observation system (using satellites and floating buoys) is considered, together with the progresses in ocean mdoelling, as one of the main causes of the recent development of the oceanographic research.

Sea surface elevation anomaly (with respect to the 1992-1997 mean level), as observed by the TOPEX/POSEIDON altimeter, from August 19 to 26, 1993. Sea surface temperature, as observed by AVHRR (Advanced Very High Resolution Radiometer), from August 19 to 26, 1993. Surface chlorophyle concentration derived from SeaWifs radiance satellite measurements (averaged from February 18 to 25, 1998).

The MEOM team contributes to the development of these systems in two different ways:

Intercomparison between altimetric observation scenarii combining 1, 2 or 3 satellites. The figure shows, as a function of the scenario, the residual error on altimetry by assimilation of these observations in an idealized model of the Gulf Stream (percentage with respect to free simulation). Salt content relative difference (between 50 and 450m) between a global DRAKKAR simulation (at 1/4 resolution) and hydrographic profiles of the ENSEMBLES/ENACT database (for the period 1980-1995).