Affiliations: Earth Observation Research Center, National Space
Development Agency of Japan, 1-9-9 Roppongi, Minato-ku, Tokyo 106-0032, Japan.
e-mail: ewa@eorc.nasda.go.jp
Abstract: The Ocean Colour and Temperature Scanner on board of the Japanese
Advanced Earth Observing Satellite has been designed to provide frequent global
measurements of marine chlorophyll levels and ocean temperature and created a
means for visualizing the biological activity in the upper ocean. Over the time
of its operation, the sensor captured the coverage of global oceans suitable
for studies of the marine primary production and monitoring of fishery sites
and environmental changes. Current radiative transfer techniques modelling
marine chlorophyll levels based on optical reflectances captured by satellite
sensors have to account for atmospheric path radiances superimposed onto the
water-leaving radiance and a diversity of water suspended particles. Detailed
modelling of geophysical processes and empirically constrained algorithms
sometimes produce misclassifications. This paper presents chlorophyll
concentration for several sites around the Pacific Ocean. Where the skill of
the conventional chlorophyll algorithm is uncertain, the results given by an
unsupervised neural network classification scheme are also provided. The
hierarchical neural network introduced in the text extracts water pixels from
images and reclassifies them to separate case 1 and case 2 waters and water
radiances with the significant influence of the atmospheric attenuation.