A feasibility study of cloud base height remote sensing by simulating ground-based thermal infrared brightness temperature measurements
地基热红外亮温遥感云底高度可行性的模拟研究

We attempt to study the feasibility of cloud base height (CBH) remote sensing by ground-based sky thermal infrared brightness temperature (Tb) observation and quantitative effects of the aerosol layer on it. Using the Modtran4.0 model simulation, the variations of Tb with zenith angle of observation for different types of aerosol and different visibilities under clear and cloudy sky conditions were systematically investigated. Based on the simulated results, the statistic equations for clear and cloudy sky Tb calculation were obtained respectively, and then a preliminary method of CBH estimation was developed. The results of simulation and preliminary experiments show that for low and middle clouds, the sky Tb observed on the ground is very sensitive to the variation of CBH, therefore it can be used to estimate CBH. The influence of aerosol (visibilities and aerosol types) above the ground on the sky Tb cannot be neglected, which must be corrected. Because the regularity of aerosol's influence on Tb with different zenith angles is fairly clear, it can be corrected well.