地基大气背景红外光谱辐射特性测量

Ground-based measurements of infrared atmospheric background spectral radiances

用傅里叶变换红外光谱辐射计（FTIR）在地面测量了较高分辨率（1 cm-1）下的大气向下背景光谱辐射,获得了长波红外5~14μm波段的大气背景辐射光谱。研究了大气背景红外光谱辐射与整层大气透过率的关系。从实验数据中研究了不同波段大气背景辐射随观测天顶角的变化。结果表明：地基大气向下的长波背景辐射亮温随着整层大气透过率的增大而减小;大气背景辐射随观测天顶角增大而增大;在大气窗口区,大气背景辐射随观测天顶角变化较快,在强吸收波段,大气背景辐射随观测天顶角几乎不变化。

The infrared atmospheric spectral radiances with high spectral resolution（1 cm-1） from sky background were measured on the ground using Fourier transform infrared radiometer（FTIR）.The background spectral radiances at infrared waveband of 5 to 14 μm were obtained.The relationship between sky spectral radiances and the vertical column atmospheric transmittance was analyzed.The distributions of sky radiances at different wavebands as a function of zenith angle were studied.Results show that the infrared waveband downwelling brightness temperatures observed on the ground decrease with the increase of vertical column transmittances;radiances increase with the increase of observing zenith angle;the atmospheric radiances vary faster with observing zenith angle at the waveband of atmospheric windows than those at the opaque waveband.The radiances are almost invariant with observing zenith angle at strong absorption wavebands.