Impact of MODTRAN®5.1 on Atmospheric Compensation

MODTRAN^reg Version 5.1 includes many new capabilities tailored to enhance and facilitate atmospheric compensation. For the thermal region, the new 0.1 cm^-1 band model provides the finer spectral resolution required for analysis of state-of-the-art long-wave and mid-wave hyper- and ultraspectral imagers (e.g. AIRS). A new MODTRAN^reg 5.1 atmospheric correction data (.acd) output file includes the specific radiative transfer quantities employed in the atmospheric compensation of solar region hyperspectral imager (e.g. MODIS, MAS) measurements; namely, DISORT-generated spectral spherical albedos and both sun-to-ground and atmospherically embedded observer-to-ground diffuse transmittances. Properly coupled observer-to-ground-to-sun path diffuse and direct transmittances are obtained when the MODTRAN^reg correlated-k model is used to generate the .acd output. Other MODTRAN^reg 5.1 features impacting both multi- and hyper-spectral atmospheric correction include the regeneration of molecular databases using HITRAN2004 with updates through January 2007, output of spectral channel brightness temperatures, input options facilitating perturbation of atmospheric profiles, and introduction of the O₂ - O₂ visible absorption continuum. Details of these capabilities are presented in the forward simulation mode along with applications in the reverse remote sensing mode to current satellite and aircraft sensors.