Preprints
https://doi.org/10.5194/amt-2021-75
https://doi.org/10.5194/amt-2021-75

  04 May 2021

04 May 2021

Review status: a revised version of this preprint is currently under review for the journal AMT.

Deriving column-integrated thermospheric temperature with the N2 Lyman–Birge–Hopfield (2,0) band

Clayton Cantrall and Tomoko Matsuo Clayton Cantrall and Tomoko Matsuo
  • Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, USA

Abstract. This paper presents a new technique to derive thermospheric temperature from space-based disk observations of far ultraviolet airglow. The technique, guided by findings from principal component analysis of synthetic daytime LBH disk emissions, uses a ratio of the emissions in two spectral channels that together span the Lyman–Birge–Hopfield (LBH) (2,0) band to determine the change in band shape with respect to a change in the rotational temperature of N2. The benefits of the two-channel ratio approach include an elimination of representativeness error as absolute LBH intensities are not required in the derivation procedure and a reduced impact of systematic measurement error caused by variations in the instrumental performance across the LBH band system as a fully resolved system is also not required. It is shown that the derived temperature should, in general, be interpreted as a column-integrated property as opposed to a temperature at a specified altitude without utilization of a priori information of the thermospheric temperature profile. The two-channel ratio approach is demonstrated using NASA GOLD Level 1C disk emission data for the period of 2–8 November 2018 during which a small geomagnetic storm has occurred. Due to the lack of independent thermospheric temperature observations, the efficacy of the approach is validated through comparisons of the column-integrated temperature derived from GOLD Level 1C data with version 2 of the GOLD Level 2 temperature product as well as temperatures from first principle and empirical models. The storm-time thermospheric response manifested in the column-integrated temperature is also shown to corroborate well with hemispherically integrated Joule heating rates, ESA SWARM mass density at 460 km, and GOLD Level 2 column O / N2 ratio.

Clayton Cantrall and Tomoko Matsuo

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-75', Anonymous Referee #1, 04 Jun 2021
  • RC2: 'Comment on amt-2021-75', Anonymous Referee #2, 07 Jul 2021

Clayton Cantrall and Tomoko Matsuo

Clayton Cantrall and Tomoko Matsuo

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Short summary
This paper presents a new technique to determine temperatures in the thermosphere from observations of far ultraviolet radiation emitted by N2. The technique utilizes a linear relationship that is established between observations and temperatures. It is shown that the derived temperatures should be treated as column-integrated quantities. Applying the technique to NASA GOLD observations results in temperatures that agree with other thermosphere observations during a geomagnetic disturbance.