夜间天空背景及云层红外辐射测量分析

Measurement of sky background and cloud infrared radiation at night

采用中波、长波红外热像仪对夜间无云天空背景及云层背景红外辐射亮度进行了测量。无云天空背景中波波段辐射亮度在0.58~1.30 W·m^(-2)·sr^(-1),长波波段辐射亮度在6.61~15.29 W·m^(-2)·sr^(-1)。由于夜间条件下无太阳辐射影响,相同俯仰观测角条件下,0°~360°各个方向天空背景辐射亮度基本一致。从无云区到有云区,随着云层厚度的增加,其辐射亮度逐渐增大。相对于无云背景,中波波段云层中心辐射亮度增加了1.5%,长波波段云层中心辐射亮度增加了14.2%,长波波段云层对天空背景辐射影响更加显著。

Infrared radiances of sky background and cloud background at night were measured by the medium wave and long wave infrared thermal imager, medium wave infrared radiance and long wave infrared radiance of cloudless sky background are 0. 58 - 1.30W·m^-2·sr^-1 ,6. 61 - 15.29 W·m^-2·sr^-1 respectively. Because of no influence of solar radiation at night, sky background radiances in all directions are almost same under the condition of the same pitch angles. From the cloudless area to the cloud area, the radiance gradually increases with the increase of cloud thickness. Compared with cloudless background, central radiance of medium wave cloud background increases by 1. 5% ,and central radiance of long wave cloud background increases by 14. 2% , so the effect of long wave band clouds on sky background radiance is more significant.