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Paul Ricchiazzi,* Shiren Yang,* Catherine Gautier,*,+ and David Sowle#
ABSTRACT
SBDART is a software tool that computes plane-parallel radiative transfer in clear and cloudy conditions within the earth's atmosphere and at the surface. All important processes that affect the ultraviolet, visible, and infrared radiation fields are included. The code is a marriage of a sophisticated discrete ordinate radiative transfer module, low-resolution atmospheric transmission models, and Mie scattering results for light scattering by water droplets and ice crystals. The code is well suited for a wide variety of atmospheric radiative energy balance and remote sensing studies. It is designed so that it can be used for case studies as well as sensitivity analysis. For small sets of computations or teaching applications it is available on the World Wide Web with a user-friendly interface. For sensitivity studies requiring many computations it is available by anonymous FrP as a well organized and documented FORTRAN 77 source code.
1. Introduction
The main driving force of the earth system is radiation forcing. The temperature and circulation of the earth atmosphere and surface are largely regulated by the amount of radiation the earth receives from the sun. The spectral composition of the radiation impacts life on earth through photosynthesis. Therefore, a detailed and quantitative knowledge of the earth radiation field is crucial to understand and predict the evolution of the components of the earth system. Until recently, the ability to compute detailed radiative quantities within the earth's atmosphere has been restricted to a relatively small group of researchers. The heavy investments of labor and computer time required to compile large molecular transmission databases and perform lengthy multiple scattering radiative transfer computations put detailed radiative transfer (RT) computations out of reach of the general geoscience community. Within the last decade, however, the development of efficient radiative transfer algorithms and freely available gaseous transmission codes, coupled with the steady improvements in computer technology have made detailed atmospheric RT modeling accessible to a much larger audience. Now, with the addition of user-friendly interfaces, the models can be used as a teaching tool, making them even more broadly usable.
Radiative transfer computer codes, such as LOWTRAN (Kneizys et al. 1983) and MODTRAN (Berk et al. 1983), have provided an accurate and expedient...