光学成像和光信息空间传输等领域需要对天空背景特性进行定性或定量的研究。Modtran等模拟计算方法无法有效模拟复杂多样的气候条件和地理环境。建立专门的测量装置获取天空背景光谱特性参数, 与理论模型计算结果进行了比对, 分析了两者的一致性和差别。通过观测数据得出: 在天空比较均匀的环境中, 天空光谱亮度通常随着太阳角的增大而减小, 当观测方向接近地平面时（大约同地平面夹角小于30°）, 天空亮度随着太阳角的增大而增大; 在晴朗无云的天空中, 光谱亮度分布偏蓝, 天空亮度主要集中在短波段部分; 在阴天和有云天观测到的天空亮度光谱明显红移。

Sky background luminance is very important in imaging and optical information transition in space. The existing sky luminance simulation codes, such as Modtran can’t be suitable for different climate and global location. Therefore, we developed a sky luminance measurement device and obtained a lot of experimental data. By analyzing these data, we found that in homogeneous sky background, the sky spectral luminance decreases with the increase of solar angle in general, but when the angle between observation direction and ground plane is less than 30°, the luminance increases with the decreasing solar angle. In fine and cloudless sky background, the sky luminance is concentrated at short-wave band, while in cloudy background there is obvious redshift of the luminance spectrum.