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

Qiuyu Chen,Ralf Koppmann,Jilin Liu,Martin Kaufmann,Martin Riese,Yajun Zhu

doi:10.5194/acp-19-13891-2019

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 %.

Highlights

In the middle and upper atmosphere, atomic oxygen (O) is mainly produced by the photolysis of molecular oxygen and ozone, and transported downward by diffusion and mixing from the thermosphere to the mesopause
A global nighttime [O] dataset is obtained by applying the OH modeling and retrieval method to the monthly zonal mean of Global Ozone Monitoring by Occultation of Stars (GOMOS) limb measurements, with the atmospheric background profiles of temperature, total density and ozone taken from the SABER measurements
Its uncertainty comes from the measurement noise, selected relaxation schemes and kinetic parameters in OH modeling and background atmosphere inputs, for example, atmospheric temperature and ozone

Summary

Introduction

In the middle and upper atmosphere, atomic oxygen (O) is mainly produced by the photolysis of molecular oxygen and ozone, and transported downward by diffusion and mixing from the thermosphere to the mesopause. The measurement of atomic oxygen dates back to before the satellite era when the MLT region was explored by means of sounding rocket experiments, hosting resonance fluorescence instruments or mass spectrometers (e.g., Dickinson et al, 1974, 1980; Sharp, 1980; Offermann et al, 1981; Sharp, 1991). They are capable of providing direct in situ measurements of atomic oxygen, it is difficult to obtain a consistent global picture of absolute density values from these measurements, which differ by a factor of more than 40 (Offermann et al, 1981; Sharp, 1991)

Results

Discussion

Conclusion