The O2(b1Σ) dayglow emissions: application to middle and upper atmosphere remote sensing1This article is part of a Special issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

Abstract

The O2atmospheric band transition is observed in the altitude region between ∼40 and 200 km in the dayglow and between ∼80 and 100 km in the nightglow. Wallace and Hunten (J. Geophys. Res. 73, 4813 (1968)) presented the first detailed analysis of the sources and sinks of this O2airglow emitting state. Because of its extended altitude coverage, bright signal, and spectral and photometric properties, this emission provides an important means to remotely sense the thermal, dynamical, and compositional structures of the upper atmosphere. In this paper we present a photochemical and emission–absorption model that calculates the spectral brightnesses of the four brightest vibrational manifolds of this band system that, for the first time, extends from the mesosphere to the thermosphere. This model incorporates the latest rate constants, cross sections, and spectral parameters relevant to this emission, some of which were not considered in previous remote sensing retrieval applications. The model results are compared with our previous rocket experiments to assess the utility of this emission for upper atmospheric remote sensing and to identify key future measurement challenges. This model, together with improved instrument capabilities, permits us to study the atmosphere from 40 up to 200 km, a region where the strongest coupling between the lower atmosphere and upper atmosphere occurs.