Inversion of "O" _"2" " 1.27 μm" nightglow emissions: A climatological analysis using satellite limb-viewed spectra and harmonic analysis method

This study employs a linear inversion algorithm to retrieve volume emission rates (VERs) of molecular "O" _"2" nightglow at "1.27 μm" , utilizing limb-viewed spectra obtained from the SCanning Imaging Absorption spectroMeter for Atmospheric for CHartographY (SCIAMACHY) payload on board the Envisat satellite. The retrieved results are compared with VERs data from the Sounding the Atmosphere by Broadband Emission of Radiation (SABER) payload on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, exhibiting the consistency. This will help to facilitate accurate revelation of spatial distribution and periodic variation in "O" _"2" nightglow. VERs are extracted monthly within the altitude range of 75-110 km from 2002 to 2012, yielding a climatology of spatial and temporal distributions. The meridional structure exhibits two maxima at equator and "45°N" , respectively. Between August and October, there is a meridional bimodal structure of the VERs, with the weaker one above the equator and the stronger one above the "45°N" . In April, the VERs reach the annual maximum. Additionally, harmonic analysis reveals significant temporal variations on different scales. The emission shows characteristics of annual and semi-annual variation, and its non-linearly long-term trend associated with the solar cycle activity.