Seasonal MLT-region nightglow intensities, temperatures, and emission heights at a Southern Hemisphere midlatitude site

Iain M Reid,Gulamabas G Sivjee,Jonathan M Woithe,Andrew R Klekociuk,Andrew J Spargo,Joel P Younger

doi:10.5194/angeo-35-567-2017

Abstract

Abstract. We consider 5 years of spectrometer measurements of OH(6–2) and O2(0–1) airglow emission intensities and temperatures made near Adelaide, Australia (35° S, 138° E), between September 2001 and August 2006 and compare them with measurements of the same parameters from at the same site using an airglow imager, with the intensities of the OH(8–3) and O(1S) emissions made with a filter photometer, and with 2 years of Aura MLS (Microwave Limb Sounder) v3.3 temperatures and 4.5 years of TIMED SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics Sounding of the Atmosphere using Broadband Emission Radiometry) v2.0 temperatures for the same site. We also consider whether we can recover the actual emission heights from the intercomparison of the ground-based and satellite observations. We find a significant improvement in the correlation between the spectrometer OH and SABER temperatures by interpolating the latter to constant density surfaces determined using a meteor radar.

Highlights

Observations of OH and O2 rotational temperatures provide a relatively simple method of routinely measuring temperatures in the atmosphere at altitudes near 87 and 94 km, respectively, at night
Inspection of these figures indicates that the OH temperatures are clearly less noisy than the O2 temperatures, and a dominant annual oscillation (AO) is evident
In the case of the O2 temperatures, both the semi-annual oscillation (SAO) and AO maximise in the autumn, with the SAO dominant at 5.1 K, about twice the magnitude of the AO at 2.6 K

Summary

Introduction

Observations of OH and O2 rotational temperatures provide a relatively simple method of routinely measuring temperatures in the atmosphere at altitudes near 87 and 94 km, respectively, at night. The OH emission in particular has been extensively studied using ground-based instruments (e.g. Semenov et al, 2013) and using satellite-based instruments (e.g. Xu et al, 2010, 2012) and has been modelled in some detail There are rather more ground-based observational sites in the Northern Hemisphere (NH) than the Southern Hemisphere (SH). Semenov et al (2013) summarise 27 NH and 9 SH sites, which includes some historical locations. Reisin et al (2014) summarise contemporary sites in the Network for the Detection of Mesospheric Change (NDMC) and include 13 NH and 6 SH sites. The addition of a new ground-based 5-year OH(6–2) and O2(0–1) rotational temperature data set from another SH site is useful

Results

Discussion

Conclusion