LOWTRAN 7: Status, Review and Impact for Short-to-Long-Wavelength Infrared Applications.

摘要

A summary of the recent improvements, modifications, and updates to the LOWTRAN 7 atmospheric transmittance and radiance computer program are given. There are some significant changes to the LOWTRAN model in the latest version, LOWTRAN 7,1,2 that affect the basic atmospheric transmittance and radiance calculations performed as well as providing the user with greater flexibility and more capabilities. The LOWTRAN 7 code now calculates atmospheric transmittance, atmospheric background radiance, single-scattered and earth-reflected solar and lunar radiance, direct solar irradiance, and multiple-scattered solar and thermal radiance. The spectral range of the code has been extended from 0 to 50,000/cm (i.e., 0.2 micrometers to infinity) at a spectral resolution of 20/cm. The program can cope with any observer/target geometry and can include the effects of molecular, aerosol, fog, rain, and cloud absorption and scattering. Some of the basic changes to LOWTRAN 7--in particular the introduction of new molecular absorption transmission functions and separating the transmittances due to CO2. N2O, CO, CH4 and O2 (previously assumed to have a combined effect)--will give rise to differences in the transmittance and radiance calculations (compared to those obtained with LOWTRAN 6) depending on the observer/target viewing geometry and spectral region. The dual purpose of this reprint is to indicate how the new changes to LOWTRAN 7 affect atmospheric transmittance and background radiance calculations for specific applications. The impact that the recent changes to LOWTRAN 7 have made on the short, medium, and long wavelength infrared atmospheric attenuation and background radiance is compared to calculations with LOWTRAN 6.