14 January 2002 Atmospheric corrections over coastal waters for SeaWiFS: validation using ground-based measurements
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We use ground-based measurements in order to validate the SeaWiFS calibration as well as the SeaWiFS atmospheric correction scheme over coastal waters. Ground-based extinction measurements provide the required information to compare to the SeaWiFS aerosol products. For most of the cases, the aerosol optical thicknesses at 865 nm agree while large discrepancies occur in the blue. The SeaWiFS algorithm quite systematically selects the maritime model while the actual aerosol models correspond to a broader variety offered by the complexity of the sources near by the European coastal areas. The radiometer also measures at several wavelengths the atmospheric downwelling radiances in the almucantar and in the principal plane (PPL). Knowing by measurements the aerosol optical thickness (tau) a, a simple scheme was developed in order to derive the aerosol phase function Pa from the PPL radiances. We then have the required inputs to a radiative transfer code to properly account for the aerosols. In a forward mode, it is then applied to simulate the signal at SeaWiFS time of overpass in order to express the TOA radiances for comparison to the SeaWiFS measurements. In a backward mode, it can be used to convert the top of atmosphere radiance into a water leaving radiance. We present here some preliminary results for 3 days over the Venice site in Italy.
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Nadege Martiny, Nadege Martiny, Richard P. Santer, Richard P. Santer, "Atmospheric corrections over coastal waters for SeaWiFS: validation using ground-based measurements", Proc. SPIE 4488, Ocean Optics: Remote Sensing and Underwater Imaging, (14 January 2002); doi: 10.1117/12.452824; https://doi.org/10.1117/12.452824

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