Using MERIS and MODIS in a near real time, global ocean colour processing for operational applications
Jacques Stum(1), Claire Pottier(2), Véronique Garçon(3) and Philippe Sicard(1)
(1) CLS, 8-10 rue Hermès, 31520 Ramonville Saint-Agne, France
(2) CNES, 18 avenue Edouard Belin, 31400 Toulouse Cedex 9, France
(3) LEGOS/CNRS, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France
Near real time, global maps of the phytoplancton concentration are produced every day at CLS for fishing resources protection and management, as well as for security applications in the offshore oil and gas industry.
MODIS/AQUA Level 2 “Quicklook” products and MERIS/ENVISAT Level 2 Reduced Resolution products, both at 1km resolution, are used as input. Basic data preprocessing consists in removing the chlorophyll values which are contaminated by cloud edges or shadows. A specific preprocessing is implemented for MERIS, which consists in reducing the across-track chlorophyll jumps induced by differences in the intercalibration of the MERIS cameras. Two mapping methods are used to build the chlorophyll maps, depending on the application needs : a simple weighted mean, or the objective analysis method. The software used for objective analysis is based on the one developed in the frame of ESA MedSpiration project for SST. It was adapted and configured for ocean colour through a CLS/LEGOS partnership (PhD Thesis by Claire Pottier). Some objective analysis parameters (e.g., the decorrelation time length) have been tuned for the near real time application, to achieve a trade-off between end users requirements and status of data accuracy and availability in real time.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,