LIMBTRAN: A pseudo three-dimensional radiative transfer model for the limb-viewing imager OSIRIS on the ODIN satellite

A new pseudo three-dimensional radiative transfer model has been written to calculate scattered light radiances required by inversion algorithms to retrieve minor species profile and column amount information from limb measurements. Stratospheric and mesospheric UV-visible limb radiances will be measured by the ODIN/OSIRIS (Optical Spectrograph and Infrared Imager System) satellite instrument to be launched in November 2000. This information will be used to study ozone depletion processes and transport dynamics in the Earth's atmosphere through the study of trace species. Model limb radiance simulations have been carried out for a suite of solar zenith and azimuthal angles and lambertian surface albedos over a broad spectral range. The effects of Rayleigh and aerosol scattering as well as ozone absorption have been modeled. Comparisons with a spherical 3-D Monte-Carlo model show that there is generally less than 3-4% difference for single-scattering and less than 10-15% and often significantly better for multiple scattering radiances at a fraction of the computational cost.