Sky-radiance measurements for ocean-color calibration-validation.
The calibration of an ocean-color sensor or validation of water products is generally based on ground-based extinct measurements from which the aerosol products (optical thickness tau(a) and aerosol type) are deduced. Sky-radiance measurements complement the extinction measurements mainly in the aerosol-model characterization. Our basic goal is to promote calibration-validation activities based on the radiative properties of the aerosols rather than their chemical or physical properties. A simple method is proposed (and evaluated) to convert sky radiances measured in the principal plane into atmospheric phase functions P. Indeed tau(a) and P are the required inputs to a radiative-transfer code for predicting the top-of-the-atmosphere radiances. The overall error in this prediction is a few percent. This method can operate on a worldwide network on ground-based sun radiometers and then be used to achieve a statistical analysis for validating satellite products.
Santer
Richard
R
Laboratoire Inter-diciplinaire des Sciences de l'Environment, Etudes des systèmes Litoraux et Cotier, Unité Mixe de Recherche 8013, Université du Littoral Côte d'Opale, 32 avenue Foch, 62930 Wimereux, France. santer@mren2.univ-littoral.fr
Martiny
Nadège
N