Simulation of Future Geostationary Ocean Color Images

Abstract

The objective of this work is to simulate global images that would be provided by a theoretical ocean color sensor on a geostationary orbit at longitude 0, in order to assess the range of radiance value data reaching the sensor throughout the day for 20 spectral bands similar to those of the Ocean and Land Color Imager (OLCI). The secondary objective is to assess the illumination and viewing geometries that result in sunglint. For this purpose, we combined a radiative transfer model for ocean waters (Hydrolight) and a radiative transfer model for atmosphere (MODTRAN) to construct the simulated radiance images at the sea surface and at the Top-Of-Atmosphere (TOA). Bio-optical data from GlobColour level 3 products are used as input maps in the ocean radiance model. The first result of this study is the radiance dynamic range of the scene during the day. The second result indicates the angular limit to avoid the sun glint phenomenon ( and ), where the viewing zenith angle, the solar zenith angle and the relative azimuth angle. We have also shown that a significant signal from water is measured when the ratio is higher than 3%, i.e., when is lower than 90, with a limit of 60 for the two angles.