Extreme Ultraviolet Variability of the Large Solar Flare on April 21, 2002 and the Terrestrial Photoelectron Response
Abstract
The near-simultaneous observations of the solar extreme ultraviolet (EUV) irradiance and terrestrial photoelectron distribution during and after the large solar flare on April 21, 2002 provide for a distinctive study of the effects that a solar flare can have on Earth's upper atmosphere. The solar EUV irradiance from 0.1-195 nm was measured by the Solar EUV Experiment (SEE) aboard the NASA Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) satellite. The terrestrial photoelectron distribution from 50-1000 eV was measured by the Fast Auroral Snapshot (FAST) energetic electron sensor. The variations of the solar EUV irradiance from the X class flare at ~2 UT on April 21, 2002 range from more than a factor of 8 for the X-ray emissions to less than 10% at longer EUV wavelengths. The spectral shape of this flare is similar to that predicted for the Bastille Day 2000 flare. Most of the solar irradiance variation is in the X-ray range and for coronal emissions. The photoelectron distribution changed by a factor of about 10 for the high-energy Auger electrons and by very little for the low-energy thermal electrons. Modeling of the photoelectron distribution using the measured solar EUV irradiance will also be presented.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMSA21B0431E
- Keywords:
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- 0358 Thermosphere: energy deposition;
- 2479 Solar radiation and cosmic ray effects;
- 7519 Flares;
- 7538 Solar irradiance;
- 7549 Ultraviolet emissions