环境一号卫星CCD相机应用于陆地气溶胶的监测

Monitoring of aerosol optical depth over land surface using CCD camera on HJ-1 satellite

环境一号卫星CCD相机应用在陆地气溶胶的监测中,因缺少短波红外通道,使地表反射的去除变得异常困难.应用改进的暗目标法,利用辐射传输方程(6S)构建查找表,对CCD相机数据进行图像重采样和辐射定标处理,进而对查找表进行插值,获得气溶胶光学厚度(AOD)分布.通过AERONET地基数据的验证及与MODIS气溶胶产品的对比表明,环境一号卫星CCD相机对陆地气溶胶的监测结果在AOD较大(>0.2)时,精度与MODIS相近;在AOD较小(<0.2)时,结果欠理想.

The potentiality of the retrieval of aerosol optic depth over land using CCD camera aboard on HJ-1A/B satellite was studied. It is very difficult to use CCD data to retrieve aerosol optic depth due to the lack of near infrared band. By using the normalized difference vegetation index （NDVI） to search for the dark pixel, a modified dark dense vegetation （DDV） method was developed to retrieve the aerosol optical depth （AOD） from CCD data. Firstly, the CCD images was re-sampled and calibrated, and then the AOD was derived using a look up table （LUT） which was built based on ＂6S＂ with the features of H J-1 CCD taken into account. The retrieved AODs were validated using ground-based observation by a CE318 sunphotometer and compared with the MODIS aerosol products. The retrieved AODs from HJ-1 CCD was in a good agreement with the MODIS AOD products when the AOD was larger than 0.2. Finally, the AOD thematic maps was obtained after smoothing AOD image.