On the detectability of solar X-ray flares using very low frequency sudden phase anomalies

dc.creatorRaulin, JP
dc.creatorPacini, AA
dc.creatorKaufmann, P
dc.creatorCorreia, E
dc.creatorMartinez, MAG
dc.date2006
dc.dateJUN
dc.date2014-11-13T12:55:51Z
dc.date2015-11-26T17:09:37Z
dc.date2014-11-13T12:55:51Z
dc.date2015-11-26T17:09:37Z
dc.date.accessioned2018-03-28T23:58:15Z
dc.date.available2018-03-28T23:58:15Z
dc.identifierJournal Of Atmospheric And Solar-terrestrial Physics. Pergamon-elsevier Science Ltd, v. 68, n. 9, n. 1029, n. 1035, 2006.
dc.identifier1364-6826
dc.identifierWOS:000238331600007
dc.identifier10.1016/j.jastp.2005.11.004
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/81697
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/81697
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/81697
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1280667
dc.descriptionWe have studied ionization excesses produced by enhancements of X-ray emission during solar flares using the very low frequency (VLF) response of the lower edge of the ionospheric D region. We focus on whether or not the X-rays associated with a given solar flare were responsible for a sudden phase anomaly (SPA) event, independently of the characteristics of the SPA. Approximately 1300 and 200 solar events were found to cause an ionospheric event, during periods of high and low solar activity, respectively. The main results of the present work are: (i) definite spectral characteristics are required for a solar flare to produce a measurable SPA; (ii) the probability of SPA occurrence due to faint solar flares, of X-ray class C1-C2 or lower, is higher during solar minimum; (iii) the same probability for more intense solar flares (class C3 or higher) does not depend on the solar activity conditions. Our observations suggest that the low ionosphere has different sensitivities depending on the solar activity, being more sensitive when the Sun is less active. These results also constitute an observational confirmation of recent findings showing that the ionospheric reference height is lower (by about <= 1 km) during solar maximum. (c) 2005 Elsevier Ltd. All rights reserved.
dc.description68
dc.description9
dc.description1029
dc.description1035
dc.languageen
dc.publisherPergamon-elsevier Science Ltd
dc.publisherOxford
dc.publisherInglaterra
dc.relationJournal Of Atmospheric And Solar-terrestrial Physics
dc.relationJ. Atmos. Sol.-Terr. Phys.
dc.rightsfechado
dc.rightshttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dc.sourceWeb of Science
dc.subjectsolar flares
dc.subjectX-rays
dc.subjectionosphere
dc.subjectsolar activity cycle
dc.subjectvery low frequency propagation
dc.subjectVlf Phase
dc.subjectD-region
dc.subjectIonosphere
dc.subjectDeviations
dc.subjectAmplitude
dc.subjectFluxes
dc.subjectCycle
dc.titleOn the detectability of solar X-ray flares using very low frequency sudden phase anomalies
dc.typeArtículos de revistas


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