VALIDATION OF MERIS-REFLECTANCE FROM FERRIES

Mounted on ferries covering most of the Norwegian coast we have sets of optical sensors mounted. Each set consist of two radiance sensors (one viewing at the surface of the sea, one at the sky) and one irradiance sensor (in addition to GPS-sensor a computer controlling the system). The collected data are used in calculating radiance reflectance which is also one of the MERIS-products. It is shown that the systems, which only requires maintainance on weekly or longer intervals, hardly are affected by deposits of salt or airborn particles. If the ferry follows an optimal transect combined with a carefull choice of observing angles (to avoid ship shaddow on the sensors footprint as well as sun-glint from the surface) it is shown that data can be collected most of the day, including during satellite passage. Then there is the satellite coverage and cloud conditions that limits the number of possible match-ups, not the shiptime which usually is the limiting factor. Our result shows typically 20% deviation between between radiance reflectance determined from MERIS and our own data.