Addressing spectral gaps when using AIRS for intercalibration of operational geostationary imagers

Comparisons between operational geostationary imagers and the high spectral-resolution Atmospheric InfraRed Sounder (AIRS), polar-orbiting on Aqua, provide a more accurate outlook on pre-existing intercalibration techniques and results. The high spectral-resolution nature of such an instrument allows more accurate comparisons of measured radiances to other instruments sharing the same spectral bandwidths, eliminating the need for knowledge of the atmospheric state which was used in forward model calculations (necessary to account for spectral response differences in broadband instruments). However, AIRS does not have complete spectral coverage and the channels on geostationary imagers where AIRS has spectral gaps, such as the water-vapor absorption region, errors are created in the comparison. The issue of spectral gaps needs to be addressed so comparisons can be made for all existing imager bands. This poster presents and analyzes one method of filling these spectral gaps for the purpose of intercalibration where a forward model is applied to an AIRS retrieval to obtain retrieved spectra in the gaps. Intercalibration of satellite radiances, which leads to an improved knowledge of calibration, is important for various global applications where data from more than one instrument are combined or compared.