An operational ocean color approach with Ve´ge´tation/SPOT-4

Demand for near-real-time (NRT) satellite ocean observations is rapidly increasing with the development of operational oceanography and its application such as ocean monitoring for offshore oil exploitation, fish resources management of detection of surface pollution. This paper demonstrates that useful NRT ocean color measurements can be deducted form the blue, red, near-infrared and SWIR bands of Ve´ge´tation on board the SPOT satellites. The data processing is based on a simple and primary algorithm. In particular, the atmospheric correction algorithm described by Fuognie, et al., (2001) is based on the use of the near-infrared B3 band to estimate aerosol amount and, assuming a unique maritime model, to extrapolate the aerosol signal to the B0 blue spectral band, the only one that is sensitive to marine reflectance. In order to increase the spatial coverage which can be sometimes very limited due to cloud coverage, a dedicated merging algorithm is used. An operational product, based on these processing algorithms is currently distributed on a commercial basis as the ocean color component into the Catsat package. Some algorithmic improvements have been studied to improve the atmospheric correction using 2 spectral bands for the selection of the aerosol model among nine. They are illustrated by results obtained using acquisitions over the Canal of Mozambique in June 2000.