所谓6S是SECOND SIMULATION OF THE SATELLITE SIGNAL IN THE SOLAR SPECTRUM的简写，直译的意思就是“太阳光谱的卫星信号二次模拟”。其前身为法国里尔科技大学大气光学实验室开发的5S（SIMULATION OF THE SATELLITE SIGNAL IN THESOLAR SPECTRUM）大气辐射传输模型。在遥感观测的太阳-目标-传感器这种模式中，无论是使用卫星或是飞机，获取数据的过程中都不可避免的受到大气的影响。6S就是为了模拟这种地气系统中的太阳辐射，计算卫星入瞳处的辐射能量(6S is a forward modeling software for remote sensing to simulate the geo-atmospheric system, not a "atmospheric correction" software, but the forward results are often used for atmospheric correction. Of course, it's not just the forward result of the output apparent radiance, but also the series of atmospheric quantities obtained during the forward process.)