Topside Ionospheric Response to Solar EUV Variability

dc.contributor.authorAnderson, Phillip C.en_US
dc.contributor.authorHawkins, Jessica M.en_US
dc.contributor.utdAuthorAnderson, Phillip C.en_US
dc.contributor.utdAuthorHawkins, Jessica M.en_US
dc.date.accessioned2016-09-27T20:46:49Z
dc.date.available2016-09-27T20:46:49Z
dc.date.created2016-02-05en_US
dc.date.issued2016-02-05en_US
dc.description.abstractWe present an analysis of 23 years of thermal plasma measurements in the topside ionosphere from the Defense Meteorological Satellite Program (DMSP) spacecraft. The H⁺/O⁺ ratio and density vary dramatically with the solar cycle; cross-correlation coefficients between E(10.7) and the daily averaged densities are greater than 0.85. The ionospheric parameters also vary dramatically with season, particularly at latitudes away from the equator where the solar zenith angle varies greatly with season. There are also 27 day solar rotation periodicities in the density, associated with periodicities in the directly measured solar EUV flux. Empirical orthogonal function analysis captures over 95% of the variation in the density in the first two principal components. The first principal component (PC1) is clearly associated with the solar EUV while the second principal component (PC2) is clearly associated with the solar zenith angle variation. The magnitude of the variation of the response of the topside ionosphere to solar EUV variability is shown to be closely related to the ionospheric composition. This is interpreted as the result of the effect of composition on the scale height in the topside ionosphere and the "pivot effect" in which the variation in density near the F(2) peak is amplified by a factor of e at an altitude a scale height above the F(2) peak. When the topside ionosphere is H⁺ dominated during solar minimum, DMSP may be much less than a scale height above the F(2) peak while during solar maximum, when it is O⁺ dominated, DMSP may be several scale heights above the F(2) peak.en_US
dc.identifier.bibliographicCitationAnderson, P. C., and J. M. Hawkins. 2016. "Topside ionospheric response to solar EUV variability." Journal of Geophysical Research A—Space Physics, doi:10.1002/2015JA021202en_US
dc.identifier.issn2169-9380en_US
dc.identifier.urihttp://hdl.handle.net/10735.1/5092
dc.language.isoenen_US
dc.publisherBlackwell Publishing Ltden_US
dc.relation.urihttp://dx.doi.org/10.1002/2015JA021202
dc.rights©2015 American Geophysical Unionen_US
dc.sourceJournal of Geophysical Research A—Space Physics
dc.subjectFunctions, Orthogonalen_US
dc.subjectIonosphere—Researchen_US
dc.subjectSolar oscillationsen_US
dc.subjectExtreme ultravioleten_US
dc.subjectPrincipal components analysisen_US
dc.titleTopside Ionospheric Response to Solar EUV Variabilityen_US
dc.type.genreArticleen_US

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