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

Abstract

Abstract. This paper presents a new dataset of nighttime atomic oxygen density [O], derived from OH(8–4) ro-vibrational band emissions, using a non-local thermal equilibrium model, with the aim of offering new insight into the atomic oxygen abundances in the mesopause region. The dataset is derived from the level-1 atmospheric background measurements observed by the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument aboard Envisat, with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measurements for the atmospheric background. Raw data are reprocessed into monthly zonal mean values in 10∘ latitude bins with a fixed altitude grid of 3 km. The dataset spans from 70∘ S to 70∘ N in latitude and from 80 to 100 km in altitude, covering a time period from May 2002 to December 2011 at local times from 22:00 to 00:00 LT. The atomic oxygen density peaks at about 95 km and the highest values are in the range of 3–8 × 1011 atoms cm−3, depending on latitude and season. There is a rapid decrease of [O] below the peak. The annual oscillation (AO), semiannual oscillation (SAO) and the solar cycle impact are distinguished from the [O] longtime series variations. This new GOMOS [O] dataset conforms to other published datasets and is consistent with the [O] datasets obtained from the Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) OH airglow measurements within about ±20 %.

Intra‐Annual Variation of Eddy Diffusion (kzz) in the MLT, From SABER and SCIAMACHY Atomic Oxygen Climatologies

“…These observations complemented studies byZhu et al (2015),Lednyts'kyy et al (2017), and followed byChen et al (2019) where amplitudes of the AO were 11%, 7%, and 9.6%, and for the SAO 15%, 12%, and 18%, respectively. The study performed byChen et al (2019) had three zones: 20-30°N, −20 to −30°S and an equatorial band. The intra-annual variation of the O density for SABER NH, SH, and EQ versus day number is shown in Figure7a, and for both SABER and SCIAMACHY in the NH in Figure7b.…”

“…The intra‐annual variation of the eddy diffusion velocity ( v ) is invariant at that altitude, but the O density is not, with measurements and analysis by Chen et al. (2019). The minimal O density below 90 km in the mid‐latitude summer is consistent with enhanced depletion and chemical O loss in summer. The analysis of k zz in the EQ region resulted in a large SAO amplitude of 25% from solstice to spring equinox, and less from solstice to fall equinox. The EQ k zz annual‐average profiles are uniform with altitude, with a value of 1.1 × 10 6 cm 2 s −1 .…”

“…The difference between the winter and summer losses of O require an AO amplitude in the downward flux (nv) at 96 km, for 10%. The intra-annual variation of the eddy diffusion velocity (v) is invariant at that altitude, but the O density is not, with measurements and analysis by Chen et al (2019). The minimal O density below…”

“…A study of O variation with season was accomplished byChen et al (2019), who measured O density oscillations using the GOMOS instrument, and analyzed the AO, SAO, and QBO amplitudes for a few years of observations. These observations complemented studies byZhu et al (2015),Lednyts'kyy et al (2017), and followed byChen et al (2019) where amplitudes of the AO were 11%, 7%, and 9.6%, and for the SAO 15%, 12%, and 18%, respectively. The study performed byChen et al (2019) had three zones: 20-30°N, −20 to −30°S and an equatorial band.…”

Comparisons of spectrally resolved nightglow emission locally simulated with space and ground level observations

“…GOMOS allowed the recovery of the OH airglow between 925 nm and 955 nm, corresponding to a part of the OH(8-4) band. Chen et al (2019) uses the R branch between 930 nm and 935 nm to retrieve global nighttime atomic oxygen abundances.…”