The Ontar Corporation is the exclusive distributor of MODTRAN5® source code for The US Air Force Research Laboratory and Spectral Sciences Inc. Included on the MODTRAN5® DVD are the FORTRAN source code and PC/Mac/Unix executables, test cases, and documentation. FORTRAN makefiles for a UNIX operating system are included for experienced users of MODTRAN5® and/or users who do not have access to a MS Windows or Macintosh environment.

MODTRAN® is an atmospheric radiative transfer model co-developed by the US Air Force Research Laboratory and Spectral Sciences Inc. The atmosphere is modeled as stratified horizontal layers and molecular and particulate constituent profiles may be defined either using built-in models or by user-specified vertical profiles. The spectral range extends from the UV into the far-infrared (0 - 50,000 cm^-1), providing resolution as fine as 0.2 cm^-1. For more information about new MODTRAN® capabilities and features, watch the official MODTRAN® web page at: www.modtran.org

MODTRAN®5 is a significant improvement over MODTRAN®4. It is highly recommended that you no longer use MODTRAN®4, or earlier version, for your atmospheric radiative transport calculations. Some of the more significant enhancements include:

• Reformulating the band model parameters and radiation transport formalism to increase the resolution of MODTRAN® spectral calculations to 0.2 cm^-1;
• Increasing the TOA solar database resolution to 0.1 cm^-1;
• Incorporating code interface changes between MODTRAN® and DISORT to increase its speed and accuracy of multiple scattering calculations;
• Upgrading MODTRAN® to perform spectral radiance computations for auxiliary molecules (by including their concentrations and spectral parameters) that are not part of the traditional MODTRAN® database; Band models are provided for all HITRAN molecular species;
• Incorporating effect of a thin layer of water, which can either simply wet the ground or accumulate on it, on radiance computations;
• Capability to model a boundary layer aerosol whose extinction coefficient obeys the Angstrom law or to modify the extinction of a model aerosol with an Angstrom law perturbation;
• Capability to determine the spherical albedo and reflectance of the atmosphere and diffuse transmittance from a single MODTRAN® run;
• Ability to include only the solar contribution to multiple scattering and ignore the thermal component where it is not significant;
• An option to write spectral output in binary, and a utility to convert the binary output to ASCII;
• Capability to process several tape5 input files by a single execution of MODTRAN®;
• Upgraded the MODTRAN®-DISORT interface so that only a single parameter (MXCMU in routine PARAMS.h) needs to be modified to change the maximum number of streams available for DISORT runs.
• Added dithering of the solar angle in cases where the DISORT particular solution to the solar problem was unstable.