Storm-time thermospheric neutral density variations: Impacts of nitric oxide cooling, and solar EUV, Particle and Joule heating
Abstract
Post-storm thermospheric mass density at a fixed altitude could be lower than the pre-storm mass density. This phenomenon has been attributed to an overcooling effect caused by enhanced infrared emissions from nitric oxide (NO). By analyzing simultaneous data from the GOCE, CHAMP, TIMED, DMSP, SOHO satellites and AMIE outputs for a few selected geomagnetic storms, we found that the apparent storm-time "overcooling" effect is a result of an increase in NO density (or cooling/energy loss rate), and/or a decrease in both the solar EUV flux and the auroral hemispheric power. It was also found that whether or not an overcooling exists depends on whether there are auroral activities prior to the pre-storm reference day and how the reference day is chosen. The relative contribution of the different drivers (namely, enhanced NO cooling and variations in auroral hemispheric power, Joule heating, and solar EUV at the pre-storm and post-storm days) remains to be determined. We note that the NO cooling alone may not be sufficient to produce the overcooling effect.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSA13B2767Z
- Keywords:
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- 0355 Thermosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3369 Thermospheric dynamics;
- ATMOSPHERIC PROCESSESDE: 2437 Ionospheric dynamics;
- IONOSPHEREDE: 2481 Topside ionosphere;
- IONOSPHERE