6S模式对EOS/MODIS数据进行大气校正的方法

探讨了运用6S模式对EOS/MODIS的可见光与近红外通道数据进行大气校正的方法和步骤,对模式中的大气模式参数和廓线的计算方法提出了改进,应用研究目标地的气象探空资料计算包括气压、温度、水汽密度和臭氧密度等大气参数和廓线,并根据海拔高度对大气廓线进行订正.实验表明:校正后的象元反射率普遍增大,反射率区间明显拉宽,表现在图像上亮度有所提高,对比度明显增加,图像层次更加丰富,图像质量得到较大改善.

The Method of Atmospheric Correction on the EOS/MODIS Data with 6S Model

EOS/MODIS as a new optical remote sense instrument can provide much information about the Earth,cloud,atmosphere,ocean,vegetation,etc.,and can be used to monitor the natural disaster and ecological environment and to study the change of global circumstance and climate.But the radiation from sun is absorbed and scattered by the atmosphere when it passes the aerosphere layer.At the same time,the long wave radiation reflected by ground is also absorbed and scattered by atmosphere.So the radiation signal received by the sensor on satellite will be distorted and attenuated.Therefore the satellite data must be performed under atmospheric correction before the remote sense image can be analyzed.6S model(the second simulation of the satellite signal in the solar spectrum) is based on the theory of radiative transfer and analyzes the landform,weather,spectrum and many other kinds of parameters synthetically.The model is not affected by the style and background of target and it has preferable precision and can be widely applied.This paper tried to use 6S model to finish the atmospheric correction of the visible light and near infrared band data of EOS/MODIS.It probed into the method and steps and improved the calculation method of atmospheric model parameter and profile in the 6S model,which meant the authors applied the weather sounding balloon data of target area into the model to calculate the atmospheric parameter and profile including the air pressure,temperature,vapor density,ozone density,etc.The method localized the atmospheric correction parameter in the model.The experiment showed that after the correction,the pixels reflectance increased generally and the reflectance range widened obviously.So the curve of pixel number on the histogram became smooth,the peak of which shifted to the right.It displayed on the image that the information of surface included in the image was richer,the brightness enhanced distinctly and contrast raised markedly.The results distinguished the noise of cloud from the interested area entirely and resumed the actual reflectance of target approximately.The fuzzy image became clear and the kinds of ground objects that can be recognized increased.The hiberarchy of image became richer,vision effect and image quality was well improved,and at the same time the inversed physics information was closer to the fact.Anyway,the result was satisfying.