Synergistic use of MODIS and AIRS: Characterization by using AIRS Level-2 atmospheric profiles and MODIS Level-2 cloud products

Several different atmospheric sounding and imaging instruments have observed a lot of information about the atmosphere, most times in isolation or with a simplified approach to combine the instruments. A careful collocation of multiple instrument observations could result in more precise or new geophysical retrievals. However, careful quantification of spectral and spatial instrument responses is necessary. In this study, we examine the combination of the high-spatial-resolution imager MODerate resolution Imaging Spectroradiometer (MODIS) with the high-spectral-resolution Atmospheric Infrared Sounder (AIRS), both mounted on the satellite platform Aqua. On one hand, MODIS has a high spatial resolution of 1 km or less and several broad-band channels in the visible and infrared spectrum that provides high-resolution cloud, aerosol, surface, and other atmospheric Level 2 retrieval products. On the other hand, AIRS has a high spectral resolution in the infrared but a relative coarse spatial resolution (13.5 km at nadir) that provides vertical profiles of atmospheric temperature and water vapor content in the Level-2 data. The overlap in the mid-infrared region provides the opportunity to compare radiances, and the spatial information of MODIS radiances and cloud products within the AIRS FOV is useful for quantifying spectral radiance behavior of AIRS. The difference between the instruments was tested under different atmospheric conditions as derived from Level-2 data of both instruments and necessary implications for a synergistic use are detected. Additionally, several leading Empirical Orthogonal Functions (EOF) of the AIRS spectrum were obtained as a function of different cloud properties as derived by MODIS and we will present differences in the characteristics of the AIRS spectra when taking into account cloud parameters from MODIS.