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

从中国北部荒漠地区输送来的亚洲沙尘(日本称为KOSA)在冬末和春季常覆盖东亚上空。亚洲沙尘又称黄沙尘。本研究的目的是利用远程输送模式和卫星资料估算亚洲沙尘的空间分布和光学特征。(1)提出了一种利用远距离逆输送模式和MODIS卫星云图识别亚洲沙尘释放区域和时间的方法。应用这种方法对2002年3月17日在日本东北和北海道地区气象站观测到的kosa现象进行了理解。结果表明，从3月15日的6h开始，沙尘粒子在(43N，114E)附近释放了约17h。(2)提出了一种利用单通道获取的ADEOS/POLDER数据同时估计亚洲沙尘的光学参数(折射率、尺度分布、光学厚度)和地表反射率的新算法。根据443 nm和670 nm通道的辐射和偏振数据，反推了沙漠地区尘埃云的光学参数和地表反射率。结果表明，除光学厚度外，443 nm通道上的参数估计值与670 nm通道上的参数估计值几乎相同。(3)利用多光谱偏振仪(PSR-1000)对日本金泽市地面站2000-2002年3-4月的天空辐射进行了偏振测量。分析了金泽市识别雾霾时测得的偏振度的波长依赖性，发现偏振的波长依赖性是由于中国沙漠输送的沙尘粒子的粒度分布所致。

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.