Comparison Of Modelled And Empirical Atmospheric Propagation Data

Airborne measurements of atmospheric transmission and path radiance in the 8-14 μm band were obtained by applying a profile calibration technique to infrared line scanner data. The profile technique involves collecting quantitative thermal infrared images over the same target areas at different altitudes. Calibration of these images to account for atmospheric effects has been demonstrated to yield computed surface tempera-tures within 0.4°C of concurrent kinetic temperature readings. Radiometric propagation models, calibrated with radiosonde data, were also used to generate transmission and path radiance values corresponding to the empirical measurements. This paper contains the results of a comparative analysis of these approaches. Some limitations of the radiometric propagation models are presented. The problems of applying atmospheric propagation models for precise quantitative analysis of satellite images are discussed. An empirical method for precise calibration of single channel satellite infrared imaging systems requiring underflight data is demonstrated and airborne test results are presented. In addition, the potential for a precise calibration approach not requiring underflight data is suggested .