Spectral line finding program for atmospheric remote sensing using full radiation transfer

We have developed a line-by-line code to simulate atmospheric spectra in the infrared spectral region assuming a remote light source of selectable temperature. Selecting the source temperature allows simulation of, for example, solar absorption spectra, lunar absorption spectra or emission spectra. The code is applicable for different geometries, from the ground, balloon or from satellite, and allows a simple search for the most suitable lines for the retrieval of atmospheric trace gas concentrations for the different geometries. In addition, a first estimate of the optimized microwindow size and the most important interfering gases that need to be considered is calculated automatically. This approach is of importance in cases where it is necessary to analyze numerous lines simultaneously to get sufficient precision in the trace gas concentration retrievals. Examples for H2O and CO are given.