Oxygen aurora during the recovery phase of a major geomagnetic storm

Abstract

[1] We have analyzed ultraviolet spectra measured in the postsunset auroral zone on 16 July 2000, during the recovery phase of the major geomagnetic storm of 14-16 July 2000. We find enhanced oxygen ion and neutral line emissions above 300 km in the postsunset sector of the auroral oval during the initial fast recovery phase of the storm, also called the Bastille Day storm. No comparable emissions are seen in simultaneous measurements of nitrogen and hydrogen emission features, indicating that these features are not related to electron or proton aurora. The enhancements are seen slightly equatorward of all other nitrogen line and band emissions that are presumed to comprise the nominal diffuse electron auroral oval. On the basis of the altitude profile, location, and timing of the enhancements, we interpret these oxygen emissions as a product of precipitating ring current oxygen ions in the auroral atmosphere, possibly after pitch-angle scattering by electromagnetic ion cyclotron waves. These emissions may provide an important measure of the contribution of collisions and charge exchange interactions to the loss of oxygen ions and the recovery of geomagnetic storms and substorms.

Astronomical sky spectra from the 29–31 October 2003 geomagnetic superstorms: Observations of O+(2Do–4So) and other emissions

“…More importantly, O + ( 2 P o – 4 S o ) 247 nm emission was observed to originate from an altitude greater than 300 km and was attributed to oxygen ions left behind at high altitudes following charge exchange collisions with ENAs. Stephan et al [2004] have conjectured that observations of O + ( 2 P o – 2 D o ) 732–733 nm emission in auroral rays seen at Sondrestrom, Greenland, that peaked in intensity at an altitude of ∼380 km [ Semeter , 2003] may also result from this process. The strongest instances of 373 nm emission in the present set of spectra occur right at the onset of the fast recovery phase, such as during the beginning of observations on 30 and 31 October.…”

“…The storm time spectra also contain features, particularly the 373 nm doublet, whose behavior may be indicative of another aurora‐like phenomenon called an oxygen aurora [ Stephan et al , 2004] or a neutral particle aurora [ Zhang et al , 2006]. The process begins with energetic neutral atoms (ENAs) and ions originating in the ring current.…”

Photoemission Phenomena in the Solar System

“…Also, the complexity and weight of ground-based instrumentation may preclude missions to space. Nevertheless, the impact of airglow studies in space has been enormous, and there is a long list of successful flight programs in which airglow has been studied (Meier 1991;Broadfoot and Bellaire 1999;Budzien et al 1994;Eastes et al 1992;Cleary et al 1995;Hecht et al 2000;Minschwaner et al 2004;Stephan et al 2004), including Atmospheric Explorer (AE), the Upper Atmospheric Research Satellite (UARS), MSX, ARGOS, and the TIMED satellite. A prime example of long-term satellite monitoring of the atmosphere is the WINDII experiment on UARS, in which a Michelson interferometer has been used to look at a variety of dayglow and nightglow emissions and to study winds and temperatures over the 80-300 km range.…”

Measurements of rovibronic line oscillator strengths of N2 in the 83.4 nm region: A high‐resolution high‐temperature study

“…The OII 83.4 nm, NII 91.7 nm, and the NII 108.5 nm lines are the prominent ion emissions in the EUV airglow [ Stephan et al , 2004; Bishop and Feldman , 2003; Link et al , 1994; Strobel et al , 1991; Meier et al , 1991, 1990; Meier , 1990; Cleary et al , 1989]. The OII 83.4 nm triplet emission is the most prominent emission below 90.0 nm in the terrestrial thermosphere.…”