Removal of Thin Cirrus Scattering Effects for Remote Sensing of Ocean Color From Space

Thin cirrus clouds frequently contaminate satellite images. These clouds are traditionally treated as aerosols in atmospheric correction processes for satellite remote sensing of ocean color. Through analysis of spectral imaging data covering a solar spectral region between approximately 0.4 and 0.9 μm and acquired with the Hyperspectral Imager for the Coastal Ocean (HICO) instrument currently on board the International Space Station, we have developed an empirical but very effective technique to remove thin cirrus effects from HICO data acquired over fairly clear ocean waters where the water leaving reflectances above 0.8 μm are close to zero. The development of the technique is based on this property and on the fact that cirrus reflectances in the 0.4-1.0-μm region are spectrally constant. The empirical technique is described, and sample results are presented. The same technique is applicable to thin cirrus corrections over clear water surfaces for other hyperspectral or multichannel imaging instruments covering similar spectral range.