Contributions of argon, nitrogen, and oxygen to air broadening in the oxygen A-band

Published

April 16, 2025

Author(s)

Leah Stevenson, Mitchio Okumura, Joseph Hodges, Erin Adkins

Abstract

The oxygen (O2) A-band is used to determine the air mass in ground- and space-based remote sensing measurements because the O2 mixing ratio in Earth's atmosphere is constant. Because errors in the retrieved air mass propagate to measurements of target gas species, accurate spectroscopic parameters are important for increasingly precise greenhouse gas measurements. However, laboratory measurements and atmospheric retrievals of this oxygen band typically neglect the line shape effects caused by collisions with argon, which comprises 0.934% by volume of the atmosphere of the Earth. To investigate the effect of argon on O2 A-band line shape parameters, we measured pressure broadening and shifting parameters for ten high J lines in the P-branch of this band. These data were acquired over a range of pressures, and N2, O2, and Ar amount fractions using frequency-agile, rapid scanning cavity ring-down spectroscopy from which respective line shape parameters for these collisional partners were determined with a multi-spectrum fitting algorithm. These results were combined with literature data to provide an empirical model for the rotational dependences of the broadening and shifting parameters by each species. Incorporating these results into a model of atmospheric column-integrated absorption spectra in the O2-A band suggests that the neglect of argon can lead to a small but potentially relevant systematic error in high-resolution atmospheric measurements of airmass.

Citation

Journal of Quantitative Spectroscopy and Radiative Transfer

Volume

342

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.jqsrt.2025.109480

Local Download

Keywords

Oxygen, line shape parameters, remote sensing

Citation

Stevenson, L. , Okumura, M. , Hodges, J. and Adkins, E. (2025), Contributions of argon, nitrogen, and oxygen to air broadening in the oxygen A-band, Journal of Quantitative Spectroscopy and Radiative Transfer, [online], https://doi.org/10.1016/j.jqsrt.2025.109480, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959398 (Accessed June 6, 2025)