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Article
Anomalous F Region Response to Moderate Solar Flares
Radio Science
  • C. G. Smithtro, Utah State University
  • Jan Josef Sojka, Utah State University
  • T. Berkey, Utah State University
  • Donald C. Thompson, Utah State University
  • Robert W. Schunk, Utah State University
Document Type
Article
Publisher
American Geophysical Union
Publication Date
1-1-2006
Disciplines
Abstract

Ionograms recorded with a dynasonde at Bear Lake Observatory, Utah, during moderate solar x-ray flares exhibit characteristic enhancements to the E and F 1 region ionosphere. However, during these same flares, the peak electron density of the ionosphere (N m F 2) unexpectedly decreases, recovering after the flare ends. In order to reconcile this anomalous behavior with expected increases to the total electron content (TEC), we undertake a modeling effort using the Time-Dependent Ionospheric Model (TDIM) developed at Utah State University. For solar input, a simple flare time irradiance model is created, using measurements from the Solar EUV Experiment instrument on the TIMED spacecraft. TDIM simulations show that the anomalous N m F 2 response can be explained by assuming a rapid electron temperature increase, which increases the O+ scale height, moving plasma to higher altitudes. The model results are able to reproduce both the decreasing N m F 2 as well as the expected TEC enhancement.

Comments
Originally published by the American Geophysical Union in Radio Science.
Citation Information
Smithtro, C. G., J. J. Sojka, T. Berkey, D. Thompson, and R. W. Schunk (2006), Anomalous F region response to moderate solar flares, Radio Sci., 41, RS5S03, doi:10.1029/2005RS003350.