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dc.contributor.authorCannon, P. S.
dc.contributor.authorHall, Chris
dc.contributor.authorBrekke, Asgeir
dc.date.accessioned2010-02-11T13:09:52Z
dc.date.available2010-02-11T13:09:52Z
dc.date.issued2007-11-29
dc.description.abstractWe have examined the long time series of observations of E-region virtual height (1948–2006) and critical frequency (1935-2006) hitherto made by the Tromsø ionosonde at 70 degrees N, 19 degrees E. Combining a simplistic trend analysis with a rigorous treatment of errors we identify a negative trend in critical frequency. While a similar analysis of the virtual height h'E also suggests a negative trend, a closer examination reveals a possible weak positive trend prior to ~1975 and a strong negative trend from ~1975 to present. These two metrics of essentially the same feature of the ionosphere do not exhibit the same signature since critical frequency is controlled by photochemistry within the E-layer while height is controlled by pressure level. We further find that the trend in critical frequency is a daylight/summer phenomenon, no significant trend being evident in the winter subset of the data. On the other hand, the trends in virtual height are independent of season/daylight.en
dc.descriptionThis is the publishers version/PDF (published in Annales Geophysicae, an open access journal of the European Geosciences Union)en
dc.format.extent481884 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.citationAnnales Geophysicae, 25, 2351–2357, 2007en
dc.identifier.issn0992-7689
dc.identifier.urihttps://hdl.handle.net/10037/2385
dc.identifier.urnURN:NBN:no-uit_munin_2135
dc.language.isoengen
dc.publisherCopernicus Publications on behalf of the European Geosciences Unionen
dc.rights.accessRightsopenAccess
dc.subjectVDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437en
dc.subjectIonosphereen
dc.subjectAuroral ionosphereen
dc.subjectIonosphereatmosphere interactionsen
dc.titleClimatic trends in E-region critical frequency and virtual height above Tromsø (70 degrees N, 10 degrees E)en
dc.typeJournal articleen
dc.typeTidsskriftartikkelen
dc.typePeer revieweden


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