Abstract

A new series of long range atmospheric transmission measurements has been performed in the 3-12 μm spectral region (1 cm^-1 resolution) over a 5.7 km horizontal path using the Fourier Interferometric Transmissometer1 (FIT). An important purpose of this experiment is the validation of atmospheric transmission models in conditions of low ambient temperature for which very few experimental data exit. Preliminary comparisons with FASCOD2² predictions has revealed a level of agreement such that the residual spectroscopic signatures from the difference between the model and measurements are difficult to validate because of experimental uncertainties. To pursue this investigation, complementary information was needed. The High resolution Interferometric Sounder³-⁴ (HIS) measurements have provided a very accurate source of additional information (absolute brightness temperature error less than 0.5 K). The analysis of uplooking and downlooking radiance measurements with the HIS are particularly relevant to this transmission study because it involves vertical propagation through cold and dry atmospheric layers.

© 1991 Optical Society of America