HR: 0830h
AN: SA41A-04    [Abstracts]
TI: Soft X-ray Irradiance during a Solar Flare
AU: * Rodgers, E M
EM: erica.rodgers@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Bailey, S M
EM: scott.bailey@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Woods, T N
EM: tom.woods@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Eparvier, F G
EM: frank.eparvier@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Drive, Boulder, CO 80303 United States
AB: Solar soft X-ray irradiance provides a highly variable energy source to the lower thermosphere. Solar flares are a dramatic source of this variability. Observations from the NASA satellite mission Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics - Solar Extreme Ultraviolet Experiment (TIMED-SEE) are being analyzed to determine how the solar soft X-ray energy deposition varies during a solar flare. The XUV Photometer System (XPS) aboard TIMED-SEE observes the solar soft X-ray irradiance between 0.1 and 27 nm for a 3 minute period approximately every 96 minutes. Contrary to initial assumptions based on the nature and infrequency of solar flares, XPS observations have shown that flares significantly impact the daily averaged energy input and thus the atmospheric chemistry of the lower thermosphere. The XPS observed, on average, eight solar flares of various strengths per month during a five month period in 2002 while the Student Nitric Oxide Explorer (SNOE) observed nitric oxide (NO) between 95 and 135 km. It has been shown that SNOE observed a significant increase in NO during the April 21, 2002 solar flare that was observed by the XPS. The eight XPS photodiodes are broadband detectors and a reference spectrum is required to interpret the signal because the sensitivity varies within each detector bandpass. A solar flare spectrum is inferred from the XPS detectors by an algorithm that iterates through differential emission measures until they produce a model spectrum that can reproduce the XPS detector observations. These flare spectra will be used to determine the soft X-ray energy input to Earth's lower thermosphere during a solar flare. Results and a description of this analysis will be presented.
DE: 2423 Ionization mechanisms
DE: 2459 Planetary ionospheres (5435, 5729, 6026, 6027, 6028)
DE: 2479 Solar radiation and cosmic ray effects
DE: 7538 Solar irradiance
DE: 7554 X rays, gamma rays, and neutrinos
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly