15 Mar 2022
15 Mar 2022
Status: a revised version of this preprint is currently under review for the journal AMT.

An optimal estimation-based retrieval of upper atmospheric oxygen airglow and temperature from SCIAMACHY limb observations

Kang Sun1,2, Mahdi Yousefi1, Christopher Chan Miller3,4,6, Kelly Chance3, Gonzalo González Abad3, Iouli E. Gordon3, Xiong Liu3, Ewan O'Sullivan3, Christopher E. Sioris5, and Steven C. Wofsy6,7 Kang Sun et al.
  • 1Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, NY, USA
  • 2Research and Education in Energy, Environment and Water Institute, University at Buffalo, Buffalo, NY, USA
  • 3Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
  • 4Climate Change Research Center, University of New South Wales, Sydney, New South Wales, Australia
  • 5Environment and Climate Change Canada, Toronto, Ontario, Canada
  • 6School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
  • 7Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA

Abstract. An optimal estimation-based algorithm is developed to retrieve number density of excited oxygen (O2) molecules that generate airglow emissions near 0.76 μm (A band) and 1.27 μm (1Δ band) in the upper atmosphere. Both oxygen bands are important for the remote sensing of greenhouse gases. The algorithm is applied to the limb spectra observed by the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument in both nominal (tangent heights below ~90 km) and mesosphere-lower thermosphere (MLT) modes (tangent heights spanning 50–150 km). The number densities of emitting O2 in the 1Δ band are retrieved in an altitude range of 25–100 km near daily in 2010, providing a climatology of O2 1Δ band airglow emission. This climatology will help disentangle airglow from backscattered light in nadir remote sensing of the 1Δ band. The global monthly distributions of the vertical column loading of emitting O2 in 1Δ state show mainly latitudinal dependence without other discernible geographical patterns. Temperature profiles are retrieved simultaneously from the spectral shapes of the 1Δ band airglow emission in the nominal limb mode and from both 1Δ and A band airglow emissions in the MLT mode. The temperature retrievals from both airglow bands are consistent internally and in agreement with independent observations from ACE-FTS and MIPAS with absolute mean bias near or below 5 K and root mean squared error (RMSE) near or below 10 K. The retrieved emitting O2 number density and temperature provide a unique dataset for remote sensing of greenhouse gases and constraining the chemical and physical processes in the upper atmosphere.

Kang Sun et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-52', Anonymous Referee #1, 15 Apr 2022
  • RC2: 'Comment on amt-2022-52', Anonymous Referee #2, 19 Apr 2022

Kang Sun et al.

Kang Sun et al.


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Short summary
This study of upper atmospheric airglow from oxygen is motivated by the need to measure oxygen simultaneously with methane and CO2 in satellite remote sensing. We provide an accurate understanding of the spatial, temporal, and spectral distribution of airglow emissions, which will help satellite remote sensing of greenhouses and constraining the chemical and physical processes in the upper atmosphere.