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Evaluation of Yellow Sand Dust in the Vegetation Index Estimated from Satellite-level Data

黄沙尘在卫星级数据估算植被指数中的评价

基本信息

批准号：
10680508
负责人：
KUSAKA Takashi
金额：
$ 2.18万
依托单位：
Kanazawa Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680508/
关键词：
Yellow Sand Dust Vegetation Index Topographic Effect NOAA AVHRR data ADEOS POLDER data Aerosol Long-range transport モンテカルロ法黄砂の光学的特性モンテカルロシミュレーション大気効果 POLDER画像東アジア浮遊粒子

项目摘要

The yellow sand dust (called "Kosa" in Japan) transported from the deserts in the northern part of China is regarded as the main source of atmospheric aerosols for East Asia in the late winter and spring. The dust particles in the atmosphere have significant effects on retrieving the surface information such as the vegetation index from satellite-level data, because the radiance received by the satellite sensor includes the skylight scattered diffusely by the yellow sand dust.(1) The distribution of hazy Kosa clouds and the optical properties of yellow sand dust were estimated, using ADEOS/POLDER data taken on April 12 and 13, 1997.The transport paths and the global mass distribution of yellow sand dust were estimated by means of the long-range transport simulation of dust particles. The result of the long-range transport simulation shows that the regions of the high concentration of yellow sand over the Sea of Japan obtained from the simulation almost correspond to the hazy Kosa regio … More ns appeared in the POLDER image. At several points selected from the hazy regions in the POLDER image, the observed reflectance's were compared with those obtained from the multiple scattering processes of light in the atmosphere-ocean system. As a result, it was found that at the 565nm channel, the refractive index of yellow sand dust is in the range from 1.45 to 1.6, and the optical thickness of atmosphere τ(565nm) is 0.42 to 0.56.(2) Topographic effects included in one pixel of NOAA/AVHRR data were evaluated.In the remote sensing of mountainous terrain, the radiance received by the AVHRR sensor is affected by the occlusion by adjacent terrain and the shadow cast by adjacent terrain. In this study, the radiance variation caused by the occlusion and shadow will be called a topographic effect. The Monte Carlo method was used to evaluate topographic effects. The 50m-mesh digital terrain model was used as the ground surface. The ratio, R, of the radiance received in rugged terrain to that in the flat terrain was computed. The following results were obtained. At the visible channel (Ch1) of AVHRR data, the value of R is larger than 0.9, not depending on the roughness of the surface. At the near infrared channel (Ch2), the value of R changes from 0.85 to 1.0, depending on the roughness of the surface when the viewing angles is smaller than 40 degrees. This indicates that the topographic effect included in AVHRR data is not so much significant. Less

从中国北方沙漠输送来的黄色沙尘（日本称“Kosa”）被认为是东亚地区冬末春初大气气溶胶的主要来源。大气中的沙尘粒子对卫星遥感数据反演植被指数等地表信息有重要影响，因为卫星接收到的辐射信息中包含了沙尘散射的天空光。(1)利用1997年4月12日和13日的ADEOS/POLDER资料，估算了灰霾科萨云的分布和沙尘的光学性质，并通过沙尘粒子的长距离输送模拟，估算了沙尘的输送路径和全球质量分布。远距离输送模拟结果表明，模拟得到的日本海黄沙高浓度区与雾状的高砂区基本一致， ...更多信息 ns出现在POLDER图像中。在POLDER图像中的模糊区域中选择几个点，将观测到的反射率与从大气-海洋系统中的光的多次散射过程获得的反射率进行比较。结果表明，在565 nm波段，沙尘折射率在1.45 ~ 1.6之间，大气光学厚度τ（565 nm）在0.42 ~ 0.56之间。(2)对NOAA/AVHRR数据中包含在一个像元中的地形效应进行了评估，在山地地形遥感中，AVHRR传感器接收到的辐射亮度会受到邻近地形遮挡和阴影的影响。在本研究中，由遮蔽和阴影引起的辐射变化将被称为地形效应。Monte Carlo方法被用来评估地形效应。地面采用50 m网格数字地形模型。计算了起伏地形与平坦地形的辐射率比R。获得了以下结果。在AVHRR数据的可见光通道（Ch 1），R值大于0.9，与地表粗糙度无关。在近红外通道（Ch 2）处，当视角小于40度时，R的值从0.85变化到1.0，这取决于表面的粗糙度。这表明AVHRR数据中包含的地形效应并不显著。少