基于查找表的MODIS逐像元大气校正方法研究

以6S大气辐射传输模型为基础,计算了气溶胶光学厚度、太阳天顶角、传感器天顶角以及地表海拔变化对于校正得到的地表反射率的影响,讨论了6S模型对于这些参数的敏感性,提出了一种基于查找表的大气校正方法,利用6S模型离线计算建立了不同气溶胶的光学厚度、太阳天顶角、传感器天顶角以及地表海拔条件下大气校正系数的查找表,基于该查找表对MODIS影像进行逐像元大气校正。通过对本文方法、6S在线校正方法和利用统一输入参数校正方法的比较表明,本文方法的计算结果与6S在线校正方法很接近,说明本文方法可以有效地改善由于大气条件、传感器位置等空间分布差异对MODIS图像大气校正的影响。

A Pixel-by-Pixel Atmospheric Correction Algorithm for MODIS Data Based on Look-up Table

Based on the 6S radiation transfer model,the influences of aerosol optical depth,solar zenith,sensor zenith and ground altitude changes on atmospheric corrected reflectances were calculated.The 6S model's sensitivities to these four parameters were discussed.A new correction algorithm based on look-up table was introduced.The look-up tables of correction parameters for different aerosol optical depth,solar zenith,sensor zenith and ground altitude values were established by the 6S model offline computation.Each pixel of MODIS data was corrected by interpolation from the look-up tables to get surface reflectance.The comparison results between our method,online method and parameter-uniform method show that the result of our method was closed to that of online method,which indicates that our method effectively reduces the influence of parameters spatial heterogeneity on atmospheric correction.