A new correlated-k algorithm has recently been incorporated into SAMM-2, the Air Force Research Laboratory 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. The underlying physical models are applicable for both low-altitude local thermodynamic equilibrium (LTE) conditions as well as high-altitude non-LTE (NLTE) conditions. Comprehensive coverage in the .4 to 40 micron (250 to 25,000 wavenumber) wavelength region for arbitrary lines-of-sight (LOS) in the 0 to 300 kilometer altitude regime is provided. A novel 1 cm-1 resolution correlated-k algorithm has been developed in order to provide the orders-of-magnitude increase in computational efficiency when compared to the existing SAMM-2 line-by-line (LBL) algorithm and applicable to both LTE and NLTE atmospheric conditions. The SAMM-2 correlated-k algorithm processes molecular lines at runtime by reading line center information from the HITRAN 2000 database and computing statistical cumulative probability distributions within a spectral interval under the presumption of a Voigt line shape profile. This algorithm is useful for treating atmospheric phenomena at all altitudes requiring a spectrally monochromatic treatment of the atmospheric transmission and/or radiance, including multiple scattering or atmospheric structure.

Date Published: 16 October 2007
PDF: 11 pages
Proc. SPIE 6745, Remote Sensing of Clouds and the Atmosphere XII, 67451M (16 October 2007); doi: 10.1117/12.738140

Published in SPIE Proceedings Vol. 6745:
Remote Sensing of Clouds and the Atmosphere XII
Adolfo Comerón; Richard H. Picard; Klaus Schäfer; James R. Slusser; Aldo Amodeo, Editor(s)