Atmospheric Radiative Transfer models (RTMs) have become important tools for the analysis and processing of optical Earth observation data. They providing meaningful links between radiometry and atmospheric composition for applications, such as aerosol radiative forcing, air quality, and atmospheric correction.
ALG facilitates consistent and intuitive user interaction, thereby streamlining model setup, running and storing RTM data for any spectral configuration in the optical domain. The following atmospheric RTMs and aerosol databases are implemented in ALG v1.2.
Note: Except for 6S, the ALG toolbox does not provide the compiled nor the source-code of the atmospheric RTM third-party software.
The MODTRAN® (MODerate resolution atmospheric TRANsmission) computer code is used worldwide by research scientists in government agencies, commercial organizations, and educational institutions for the prediction and analysis of optical measurements through the atmosphere. MODTRAN was developed and continues to be maintained through a long-standing collaboration between Spectral Sciences, Inc. and the Air Force Research Laboratory. The code is embedded in many operational and research sensor and data processing systems, particularly those involving the removal of atmospheric effects, commonly referred to as atmospheric correction, in remotely sensed multi- and hyperspectral imaging.
The 6S code is a basic RT code used for calculation of lookup tables for the atmospheric correction of satellite and airborne sensors. It enables accurate simulations of observation in the 400-2500 nm spectral range at 2.5 nm spectral resolution, accounting for elevated targets, use of anisotropic and lambertian surfaces and calculation of gaseous absorption. The code is based on the method of successive orders of scatterings approximations and its vector version (6SV) is capable of accounting for radiation polarization.
The software package OPAC (Optical Properties of Aerosols and Clouds) is an aerosol and cloud model, consisting of microphysical description of aerosol, as a combination of variable components, and clouds with different types.