21 April 2011
Better sea-state forecasting
After TOPEX/Poseidon, AltiKa and the Jason satellites, CFOSAT is the latest in a long line of oceanography projects for which CNES is a renowned centre of excellence,” says Patrick Castillan, CFOSAT Project Leader at CNES’s Toulouse Space Centre.
Unlike its predecessors, CFOSAT (China-France Oceanography SATellite) will not be measuring sea-surface height but determining the direction, amplitude and wavelength of surface waves in order to characterize what oceanographers call “sea state”.
For this purpose, it will be carrying SWIM (Surface Wave Investigation and Monitoring), a highly innovative measuring instrument developed by Thales Alenia Space in Toulouse.
“SWIM is a radar with 6 rotating beams that will hit waves at a given angle of incidence to determine their frequency and thus deduce their physical properties,” explains Patrick Castillan.
This French instrument will operate alongside the Chinese SCAT instrument, a conical-scanning scatterometer designed to measure wind speed.
Why measure wind and waves? Because the two phenomena are interlinked: waves are generated by wind energy. And that is why wind is one of the main meteorological variables in sea-state forecasting models.
Being able to forecast sea state is vital in many domains like shipping, offshore operations, shipbuilding, safety at sea and in coastal areas, and drifting of marine pollution.
The science team headed by Danièle Hauser at the LATMOS1 atmospheres, environments and space observations laboratory, the national weather service Météo-France and Ifremer2, the French institute of marine research and exploration, are all eagerly awaiting CFOSAT data to improve their understanding of surface processes, which are key elements in predictive models.
Marine meteorology and scientists working to improve knowledge of climate variability will be the main long-term beneficiaries of CFOSAT data.
A research mission developed for LATMOS in France and China’s National Satellite Ocean Application Service (NSOAS), CFOSAT is also a pre-operational mission for Météo-France and the European Centre for Medium-range Weather Forecasts (ECMWF).
Ultimately, data from both instruments on CFOSAT could be assimilated into the GMES/MyOcean system.
The satellite will be orbited by a Chinese Long March 2C launcher and should be operational in 2015. Data will be received and processed at French and Chinese receiving stations.
1 Laboratoire ATmospheres, Milieux, Observations Spatiales
2 Institut FRançais de recherche pour l’Exploitation de la MER