Using the MODTRAN Tm5 radiative transfer algorithm with NASA satellite data:: AIRS and SORCE

Testing MODTRAN (TM) 5 (MOD5) capabilities against NASA satellite state-of-the-art radiance and irradiance measurements has recently been initiated. New solar data have been acquired from the SORCE satellite team, providing measurements of variability over solar rotation cycles, plus an ultra-narrow calculation for a new solar source irradiance, extending over the full MOD5 spectral range. Additionally, a MOD5-AIRS analysis has been undertaken with appropriate channel response functions. Thus, MOD5 can serve as a surrogate for a variety of perturbation studies, including two different modes for including variations in the solar source function, Io: (1) ultra-high spectral resolution and (2) variations due to solar activity and rotation. The comparison of AIRS-related MOD5 calculations, against a suite of 'surrogate' data generated by other radiative transfer algorithms, all based upon simulations supplied by the AIRS community, provide validation in the Long Wave Infrared (LWIR). All similar to 2400 AIRS instrument spectral response functions (ISRFs) are expected to be supplied with MODTRAN (TM) 5. These validation studies show MOD5 replicates line-by-line (LBL) brightness temperatures (BT) for 30 sets of atmospheric profiles to approximately -0.02 degrees K average offset and < 1.0 degrees K RMS.