Influence Of Absorptive Aerosols On Atmospheric Correction Algorithm In The East Asian Area And Ocean Color Related Issues

The development of ocean color techniques,related algorithms and the existing problems in ocean color were described. The radiative transfer theory and the major optical properties of atmosphere and ocean were also introduced. Based on the ACE-Asia measurements, it was concluded that the under-estimation of shorter wavelength was a common phenomenon in the East-Asian area. Using an optimization method, information on the possible composition of aerosols was obtained. An iterative radiative transfer simulation was carried out, in an attempt to reproduce the satellite–measured top-of-atmosphere reflectance. The resulting water reflectance and aerosol optical thickness agreed well with in situ measurements when the effect of sub-micron absorbing particles was considered in the radiative transfer simulation. The error in the retrieved water reflectance was much reduced. The effect of the Asian dust was also simulated in comparison with that of small absorptive aerosols. The under-estimation could not be solely attributed to Asian dust. It was also found that, at one of the stations where the presence of dust aerosols was anticipated, an aerosol model mixed with both dust and soot improved the accuracy of the estimated AOT compared with the case of soot as the only absorptive aerosol. Sub-micron absorbing particles, in addition to the Asian dust, should be considered in the optical remote sensing of East-Asian waters. Source and coverage of soot aerosol and their effect on different water types were discussed. The relationship of beam attenuation coefficient and diffused attenuation coefficient was achieved from radiative transfer simulation. The remote sensing algorithm of Secchi Disk depth was obtained and then validated with the in situ measurements which produces quite good agreements. Secchi Disk depth distribution from 1997-2001 was retrieved in the Eastern China Seas using this algorithm. Preliminary analysis was carried out. Finally, some biological and oceanographic features were revealed and analyzed using SeaWiFS-derived chlorophyll a concentration.