Optical properties of Asian dust aerosol by SeaWiFS and contemporaneous ground observation data

Asian dust aerosol layer of 4-6 km altitude accompanied by low clouds was observed with a LIDAR in Tokyo urban area on April 10 2001. In addition, column-integrated size distribution of aerosol was measured with a SkyRadiometer. To synthesize the top of atmosphere (TOA) reflectance, radiative transfer simulation was conducted assuming aerosol/cloud vertical structure and aerosol size distribution that were estimated after the ground observations. The refractive index of Asian dust was derived from a laboratory measurement of sampled Chinese soil particles. The synthesized TOA reflectance was compared to the SeaWiFS-derived one sampled at the low cloud pixels whose airmass is the same as the one passed at the observation site. TOA reflectance of the one of Asian dust models compare generally well with few percent difference in reflectance. We estimated an affect of Asian dust aerosol to ocean color remote sensing. Simulated TOA radiance absorbed by Asian dust was 20.0 W/m2/μm/sr in 443 nm. It is suggest that the existence of Asian dust occurs to dervie negative water-leaving radiance.