Modeling and experimental validation of full-sky background radiance characteristics using CART

Abstract

Sky background radiance serves as a crucial background element in optical imaging, target detection, and atmospheric remote sensing. This study assesses the capability of the CART radiative transfer model to replicate the characteristics of full - sky background radiance. It does so by comparing the model simulations with the measurements obtained from a spectral full - sky background radiometer in typical regions. The angular and spectral variations of sky radiance are examined under different viewing geometries. Additionally, comparisons between the model results and measurements are carried out for representative broadband and narrowband integrations. The calculated full - sky radiance distributions exhibit a good agreement with the overall angular patterns of the measured data. However, the most significant discrepancies are observed at small forward - scattering angles, as it is challenging to represent real aerosol phase functions using simplified aerosol models. For representative cloud - free directions, the maximum mean relative error of the reported comparison groups is less than 9.6%. This indicates that the CART model can provide reliable full - sky background radiance simulations for infrared target - background analysis and atmospheric transmission studies.