Optical properties of the atmosphere: calculated variability and application to satellite remote sensing of phytoplankton.

The radiative transfer equation is solved by the method of successive orders of scattering for several different model atmospheres, taking into account the realistic variability of scattering and absorption. A windruffled ocean surface with whitecaps and with different phytoplankton content is also taken into account. The variation of the ocean-leaving radiance when traveling through the atmosphere is investigated. Calculations are performed at five wavelengths from 0.443 to 0.750 microm, according to the channels of the Coastal Zone Color Scanner (CZCS) on board the Nimbus 7 satellite. The radiance reaching the satellite amounts to only 5% of the radiation that penetrated the ocean, and consequently 95% of the radiation is scattered in the atmosphere or reflected at the ocean surface. Radiance variation at the satellite due to phytoplankton variations lies on the order of 1%, while the radiance variation due to the realistic spread of the optically relevant atmospheric and oceanic constituents is considerably higher. The variability of the atmospheric turbidity already causes changes up to 10% in the radiance at the satellite.