Anomalous F Region Response to Moderate Solar Flares

Authors

C. G. Smithtro, Utah State University
Jan Josef Sojka, Utah State UniversityFollow
T. Berkey, Utah State UniversityFollow
Donald C. Thompson, Utah State UniversityFollow
Robert W. Schunk, Utah State UniversityFollow

Document Type

Article

Journal/Book Title/Conference

Radio Science

Volume

41

Issue

RS5S03

Publisher

American Geophysical Union

Publication Date

2006

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.

Recommended Citation

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.