The estimation of the advection diffusion and the optical characteristics of the Asian dust using satellite_level data

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The Asian dust (called "Kosa" in Japan) transported from desert areas in the northern part of China often covers over East Asia in the late winter and spring.The Asian dust is also called yellow sand dust.The objectives of this study are to estimate the spatial distribution and the optical characteristics of the Asian dust using the long-range transport model and satellite_level data.The following results were obtained :(1) A method for identifying the released region and time of yellow sand dust using the long-range inverse transport model and MODIS satellite images was proposed. This method was applied to understand Kosa phenomena observed at meteorological stations in Tohoku and Hokkaido districts, Japan on March 17, 2002. As a result, it was found that dust particles were released during about 17 hours from 6h on March 15 in the neighborhood of (43N, 114E).(2) A new algorithm for estimating optical parameters (refractive index, size distribution, optical thickness) of the Asian dust and the surface reflectance simultaneously from ADEOS/POLDER data acquired at a single channel was proposed. Optical parameters of the dust cloud over a desert area and the surface reflectance were estimated inversely from the radiance and polarization data at each of 443nm and 670nm channels. As a result, it was found that the values of parameters estimated at the 443nm channel are almost the same as those at the 670nm channel except for the optical thickness.(3) Polarization measurements of the sky radiation by the multi-spectral polarimeter (PSR-1000) at the ground station in the Kanazawa city, Japan from March to April in 2000 to 2002 have been made. The wavelength dependency of degrees of polarization measured when the hazy dust was recognized in the Kanazawa City was analyzed and it was found that the wavelength dependency for polarization will be due to the size distribution of dust particles transported from the deserts in China.