可见光-近红外通道数据大气校正方法研究

Visible Light to Near Infrared Channel Data for Atmospheric Correction Methods Research

针可见光-近红外通道数据进行大气校正,提升可见光-近红外通道数据的可靠性。进行大气校正时,应获取可见光-近红外光谱响应函数,建立可见光-近红外通道数据校正所需的查找表,但传统方法不能获取精确的对可见光-近红外光谱响应函数,进行大气校正时出现较大偏差。提出一种基于6S模型的Himawari-8可见光-近红外通道数据的大气校正方法。在6S大气辐射传输模型中加入可见光与近红外光谱响应函数,进行辐射传输模拟并对所需输入的参数做敏感性分析后,建立包含太阳天顶角、卫星天顶角、相对方位角、气溶胶光学厚度、臭氧含量、水汽含量、表观反射率等参数的查找表。利用查找表对Himawari-8可见光与近红外波段数据进行逐像元大气校正。从反射率值、归一化植被指数(NDVI)、MODIS地表反射率三个方面,分析6S模型查找表法大气校正的效果。仿真结果表明:选用的校正方法有效,校正后Himawari-8可见光与近红外波段数据范围加宽,各波段反射率更平滑,能区分的地物信息更多;校正后各波段NDVI和MODIS值更接近实际情况,说明选用方法具有较高的校正精度。

Atmospheric correction can improve the reliability of visible light - near infrared channel data. During correction, it should obtain spectral response function of visible light - near infrared and build the look - up table needed for channel data correction. However, traditional method cannot obtain the precise spectral response function. It leads to big deviation during correction. In this paper, we proposed a Himawari -8 atmospheric correction method of visible light - near infrared channel data based on 6S model. Firstly, we added spectral response function of visible light and near - infrared light into the 6S atmospheric radiation transfer model. Then the radiation transfer was simu- lated and the sensitivity analysis was made to parameters needed for inputting. After that we built the look - up table containing many parameters such as the solar zenith angle, satellite zenith angle, relative azimuth angle, aerosol opti- cal thickness, ozone content, moisture content, and apparent reflectance. We also used the look -up table to make atmospheric correction, one by one pixel to data of visible light and near infrared band. Finally we analyzed the cor- rection effect of look - up table method based on 6S model from the aspects of reflectance value, normalized differen- tial vegetation index （NDVI） and MODIS surface reflectance. The simulation results show that the selected correction method is effective. It broadens the data field of Himawari - 8 in visible light and near infrared band. The reflectivity of each band is smoother and distinguished ground information is more. The NDVI and MODIS value is closer to actu- al condition after correction. It proved the selected method has higher correction precision.