Raphael Panfili (Spectral Sciences, Inc.), Hoang Dothe (Spectral Sciences, Inc.), John Gruninger (Spectral Sciences, Inc.), James W. Duff (Spectral Sciences, Inc.), James H. Brown (Air Force Research Laboratory)
Keywords: Astronomy, Astronomical Catalogs
Abstract:
This talk describes recent upgrades to SAMM-2, a background radiance and transmission code. SAMM-2 incorporates all of the major components necessary for background scene generation at all altitudes: atmospheric characterization, solar irradiance, molecular chemical kinetics and molecular spectroscopic data. In addition, it seamlessly combines MODTRAN, a standard low-altitude local thermodynamic equilibrium model (LTE), with SAMM-1 and SHARC, standard high-altitude non-local thermodynamic equilibrium models (NLTE) to form a single, unified code with comprehensive coverage in the .4 to 40 micron (250 to 25,000 wavenumber) wavelength region for arbitrary lines-of-sight in the 0 to 300 kilometer altitude regime.
Efforts are currently underway to upgrade SAMM-2 from a code primarily used for line-of-sight computations to an efficient scene generator. The inclusion of new, high-efficiency radiation transport (RT) algorithms is central to this upgrade. To this end, Spectral Sciences, Inc. (SSI) has developed an NLTE correlated-k RT model which provides a factor-of-100 speed increase over the existing line-by-line model (QBL) in SAMM-2. This model is able to simulate atmospheric stochastic structure as defined by a temperature and density fluctuation model in addition to clear atmosphere radiance and transmission. In addition, a new NLTE band model developed by SSI provides a factor-of-1000 speed increase over the QBL model.
The proliferation of RT algorithms within SAMM-2 provides the impetus to open SAMM-2 to a wider developer community. SAMM-2 will communicate with its RT algorithms through a well-defined interface. This interface will guarantee inter-operability while allowing for independent development of SAMM-2 and the third-party algorithms in the future. This approach will allow cutting-edge RT algorithms can be rapidly incorporated without the need to develop new atmospheric characterization and molecular chemistry components.
Date of Conference: September 12-15, 2007
Track: Astronomy and Astronomical Catalogs