Model results of OH airglow considering four different wavelength regions to derive night-time atomic oxygen and atomic hydrogen in the mesopause region

Abstract

Based on the zero-dimensional box model Module Efficiently Calculating the Chemistry of the Atmosphere/Chemistry As A Box model Application (CAABA/MECCA-3.72f), an OH airglow model was developed to derive night-time number densities of atomic oxygen ([O( 3 P)]) and atomic hydrogen ([H]) in the mesopause region (∼ 75-100 km). The profiles of [O( 3 P)] and [H]were calculated from OH airglow emissions measured at 2.0 µm by the Sounding of the Atmosphere using Broadband Emission Radiography (SABER) instrument on board NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. The two target species were used to initialize the OH airglow model, which was empirically adjusted to fit four different OH airglow emissions observed by the satellite/instrument configuration TIMED/SABER at 2.0 µm and at 1.6 µm as well as measurements by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument on board the Environmental Satellite (ENVISAT) of the transitions OH(6-2) and OH(3-1). Comparisons between the "best-fit model" obtained here and the satellite measurements suggest that deactivation of vibrationally excited OH(ν) via OH(ν ≥ 7)+O 2 might favour relaxation to OH(ν ≤ 5)+O 2 by multi-quantum quenching. It is further indicated that the deactivation pathway to OH(ν = ν − 5)+O 2 dominates. The results also provide general support of the recently proposed mechanism OH(ν)+O( 3 P)→OH(0 ≤ ν ≤ ν−5)+O( 1 D) but suggest slower rates of OH(ν = 8, 7, 6, 5)+O( 3 P), partly disagreeing with laboratory experiments. Additionally, deacti-vation to OH(ν = ν − 5)+O( 1 D) might be preferred. The profiles of [O( 3 P)] and [H] derived here are plausible between 80 and 95 km but should be regarded as an upper limit. The values of [O( 3 P)] obtained in this study agree with the corresponding TIMED/SABER values between 80 and 85 km but are larger from 85 to 95 km due to different relaxation assumptions of OH(ν)+O( 3 P). The [H] profile found here is generally larger than TIMED/SABER [H] by about 50 % from 80 to 95 km, which is primarily attributed to our faster OH(ν = 8)+O 2 rate.

Observations and Modeling of Potassium Emission in the Terrestrial Nightglow

“…Atomic oxygen is derived from OH nightglow emission (Mlynczak et al, , 2018. Although the debate on the best retrieval approach is still ongoing (Fytterer et al, 2019;Panka et al, 2018;Zhu & Kaufmann, 2018), the systematic uncertainties in n O appear to be sufficiently small for our study. The selection of the profiles for the different properties was restricted to an area around Cerro Paranal with maximum latitudinal and longitudinal deviations of 5 • and 10 • , respectively.…”

Global nighttime atomic oxygen abundances from GOMOS hydroxyl airglow measurements in the mesopause region

“…Some new findings on airglow relaxation modeling and reaction kinetic parameters were recently published. A new pathway, in which highly vibrationally excited OH radicals (v ≥ 5) are deactivated by atomic oxygen to a lower state (0 ≤ v ≤ v − 5), is proposed and discussed (Sharma et al, 2015;Kalogerakis et al, 2016;Panka et al, 2017Panka et al, , 2018Fytterer et al, 2019;Kalogerakis, 2019). These results complicate the topic further.…”

Nighttime O(<sup>1</sup>D) distributions in the mesopause region derived from SABER data

“…All processes used for O( 1 D) determination are summarized in Table 1. Here, we apply the new OH(v) model of Fytterer et al (2019). Their "best-fit model" includes all commonly used production and loss processes of OH(v) (see Table 1), but some parameters of the model, in particular, branching ratios of quenching OH(v)+O 2 and rate coefficients of OH(ν≥5) + O( 3 P) → OH(0≤ν ' ≤ν-5) + O( 1 D) were adjusted with the use of volume emission rate profiles in four different wavelengths measured by SABER and SCIAMACHY.…”