Quantifying uncertainties in Atmospheric Infrared Sounder (AIRS) spatial response functions

Quantifying uncertainties in Atmospheric Infrared Sounder (AIRS) spatial response functions (SpatialRFs) is critical for enhancing the quality of climate data records. Previously, AIRS in-flight SpatialRF calibrations have utilized an incomplete set of pre-flight data obtained during instrument assembly. In our current work, we combined various pre-flight data sets to interpolate a complete set of pre-flight SpatialRFs. Concurrently, we employed two consecutive days of AIRS and Moderate Resolution Imaging Spectroradiometer (MODIS) data to independently retrieve in-flight SpatialRFs for multiple channels and scan angles. Our methodology, based on our previous work, aligns AIRS and MODIS radiances to derive spatially corrected SpatialRFs. This paper compares in-flight SpatialRFs obtained from consecutive days and examines the discrepancies between pre-flight SpatialRFs from a completed set and in-flight SpatialRFs. Employing the total variation distance metric with two days of consecutive data revealed that the average uncertainties in in-flight SpatialRFs are approximately 5\%, attributed mainly to noise, which establishes a baseline. In contrast, pre-flight SpatialRFs displayed an average uncertainty of about 16\% when compared to the values derived in-flight. Our findings underscore the value of reconstruction techniques to derive in-flight SpatialRFs to validate pre-flight measurements, which is vital for ensuring the long-term reliability and precision of climate data records obtained from AIRS.