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

从中国北部的沙漠中运输的黄色沙尘（称为“ Kosa”）被认为是冬季和春季后期东亚大气气溶胶的主要来源。大气中的尘埃颗粒对检索表面信息（例如从卫星水平数据中的植被指数）具有重大影响，因为卫星传感器所收到的辐射包括散布的天窗因黄色砂尘而散布。通过对灰尘颗粒的远程传输模拟估算黄色的砂尘。远程传输模拟的结果表明，从模拟获得的日本海洋上高浓度的黄色沙子的区域几乎对应于朦胧的Kosa区域……在Polder图像中出现了更多的NS。在从Polder图像中选择的几个点上，将观察到的反射率与从大气 - 海洋系统中光的多个光散射过程中获得的反射率进行了比较。结果，发现在565nm的通道上，黄色沙尘的折射率在1.45到1.6范围内，大气厚度τ（565nm）的光厚度为0.42至0.56至0.56。受到邻近地形和相邻地形铸造的阴影的影响。在这项研究中，由阻塞和阴影引起的辐射变化将称为地形效应。 Monte Carlo方法用于评估地形效应。 50m-mesh数字地形模型被用作地面。计算了在坚固的地形中收到的辐射的比率。获得以下结果。在AVHRR数据的可见通道（CH1）上，R的值大于0.9，不取决于表面的粗糙度。在近红外通道（CH2）上，R的值从0.85变为1.0，具体取决于表面的粗糙度，当视角小于40度时。这表明AVHRR数据中包含的地形效应并不重要。较少的