Updates to the radiometric calibration of the Atmospheric Infrared Sounder (AIRS)

Thomas S. Pagano; Evan M. Manning; Steven E. Broberg; Hartmut Aumann; Robert C. Wilson; Ken Overoye

doi:10.1117/12.2676416

4 October 2023 Updates to the radiometric calibration of the Atmospheric Infrared Sounder (AIRS)

Thomas S. Pagano, Evan M. Manning, Steven E. Broberg, Hartmut Aumann, Robert C. Wilson, Ken Overoye

Proceedings Volume 12685, Earth Observing Systems XXVIII; 126850K (2023) https://doi.org/10.1117/12.2676416
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua spacecraft measures the upwelling radiance of the atmosphere from 3.7 to 15.4 μμm. The AIRS radiometric calibration coefficients convert the counts measured from the instrument’s A/D converters (Level 1A) to SI traceable radiance units (Level 1B). The calibration equations are based on how the instrument operates and follow a simple second order relationship between counts and radiance. Terms are included to account for nonlinearity of the detectors, emissivity and temperature knowledge of the on-board calibrator (OBC) blackbody and radiometric offset due to coupling of the polarization of the scan mirror with the spectrometer. Radiometric coefficients have not been updated since launch and are used in the operational Version 5 available at the GES/DISC. A new set of coefficients, Version 7 (V7), were produced in 2018 but never released. This paper presents the coefficients for Version 8 (V8) with only a few changes from V7 relating to the additional time used in the training of the trend of the polarization coefficients. We then compare new coefficients, V8, with the latest operational version of the AIRS radiometric calibration coefficients Version 5 (V5) and the prior V7. The Version 8 coefficients utilize more of the pre-flight test data and show lower residuals to the tests than V5. V8 also removes a trend in the polarization seen in Module 5 and is expected to have more accurate nonlinearity than prior versions.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Thomas S. Pagano, Evan M. Manning, Steven E. Broberg, Hartmut Aumann, Robert C. Wilson, and Ken Overoye "Updates to the radiometric calibration of the Atmospheric Infrared Sounder (AIRS)", Proc. SPIE 12685, Earth Observing Systems XXVIII, 126850K (4 October 2023); https://doi.org/10.1117/12.2676416

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