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Anomalous F region response to moderate solar flares
Author(s) -
Smithtro C. G.,
Sojka J. J.,
Berkey T.,
Thompson D.,
Schunk R. W.
Publication year - 2006
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2005rs003350
Subject(s) - tec , solar flare , ionosphere , physics , flare , total electron content , solar maximum , atmospheric sciences , astrophysics , solar minimum , electron density , extreme ultraviolet lithography , electron , irradiance , plasma , computational physics , solar cycle , astronomy , optics , solar wind , quantum mechanics
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.