Thermospheric Nitric Oxide Density Enhancement due to Solar Flares
Abstract
Solar soft X-rays are one of the principal energy sources that lead to the production of low latitude thermospheric nitric oxide (NO). The density of NO peaks in the lower thermosphere near 110 km. NO has a lifetime of about one day in the thermosphere and the rate of equatorial NO production responds linearly to the daily soft X-ray energy deposited at the peak altitude. Solar flare soft X-ray irradiance provides a highly variable energy source to the lower thermosphere. During a solar flare, the overall soft X-ray irradiance between 0.1-7 nm is increased with most of the increase between 0.1-2 nm. The excess of 0.1-2 nm soft X-rays leads to more NO production near 110 km. NO plays an important role in the energy balance of the thermosphere as it is a source of radiative cooling due to infrared emissions. Therefore, solar flare enhanced NO leads to increased cooling of the thermosphere through these emissions. Observations from the Student Nitric Oxide Explorer (SNOE) are analyzed to determine how the solar flare soft X-ray irradiance affects the Earth's lower thermosphere. SNOE observed a significant increase in thermospheric NO following the X17 solar flare on 28 October 2003. Analysis of solar flare NO density enhancements and comparisons to results from a photochemical model will be presented.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMSA13A0266R
- Keywords:
-
- 0355 Thermosphere: composition and chemistry;
- 0358 Thermosphere: energy deposition (3369);
- 7519 Flares;
- 7538 Solar irradiance