Integrated Horizontal Line-of-Sight TAWS Model

To estimate the diffuse solar radiative flux for visual wavelengths in the atmosphere, TAWS (Target Acquisition Weapons Software) currently employs a delta-Eddington method combined with a plane-parallel atmospheric model. This method and the plane-parallel atmospheric model do not provide sufficient accuracy for HLOS calculations. To handle Army HLOS scenarios, TAWS requires a new technique to compute the diffuse solar radiative flux for visual wavelengths. While exact radiative transfer techniques can calculate this flux accurately, their direct application is too computationally expensive for use in deployed target acquisition and mission planning software. ThermoAnalytics, in conjunction with Northrop Grumman, and Atmospheric Physics professor Dr. Alex Kostinski, proposes an alternative approach of combining an interpolation procedure with the newly improved MODTRAN 4v3r1-based scaled Isaac's 2-stream multiple scattering option. This recent MODTRAN improvement uses DISORT calculations performed at a few fixed spectral points with an external interpolation scheme to reduce the required number of path calculations while achieving near-DISORT accuracy in the 400-700 nanometer band. The interpolation procedure will be designed around the TAWS software architecture. This task will require tuning under various TAWS scenarios to determine optimal strategy for balancing speed and accuracy.