Daytime electron density at the F1-region in Europe during geomagnetic storms

Burešová, Dalia; Laštovička, Jan; Altadill, D.; Mirò, G.

doi:10.5194/angeo-20-1007-2002

Cited by 30 publications

(24 citation statements)

References 19 publications

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“…Also these plots show a decrease in the F 1 region ionization during the positive storm phase. The large positive effect in F 2 region accompanied by a negative effect at F 1 region heights (∼150-200 km) agrees with finding by Buresova et al (2002) that storm effects at F 1 region heights at European higher middle latitudes are always negative. However, it must be noted that this effect in F 1 region is more pronounced in COSMIC-derived electron density profiles (Figs.…”

Section: Resultssupporting

confidence: 80%

Observation of the ionospheric storm of October 11, 2008 using FORMOSAT-3/COSMIC data

et al. 2012

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The electron density profiles retrieved from the COSMIC radio occultation measurements were examined in order to estimate the possibility of its use as additional data source to study changes in electron density distribution occurred during ionospheric storms. The ionosphere behaviour during moderate geomagnetic storm which occurred on October 11, 2008 was analysed. The short-duration positive effect was revealed distinctly in GPS TEC and ionosonde measurements. For the European mid-latitude region it reached the factor of 2 or more relative to the undisturbed conditions. COSMIC data were analyzed and their validity was tested by comparison with ground-based measurements. It was shown the good agreement between independent measurements both in quiet and disturbed conditions. Analysis of COSMIC-derived electron density profiles revealed changes of the bottom-side and topside parts of the ionosphere.

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Section: Resultssupporting

confidence: 80%

Observation of the ionospheric storm of October 11, 2008 using FORMOSAT-3/COSMIC data

et al. 2012

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“…The results by Buresova and Lastovicka (2001) and Buresova et al (2002) show some seasonal effect (winter/summer and autumn/spring asymmetry) in the NeF1 reaction to the geomagnetic disturbances. We have calculated average rNe from Tables 1 and 2 for different seasons.…”

Section: Discussionmentioning

confidence: 86%

“…Therefore, the observed small reaction of the F1-region to the geomagnetic disturbances followed by large perturbations in the thermospheric parameters is interesting from a physical point of view and should be explained. Recently, Buresova and Lastovicka (2001), and Buresova et al (2002) have attempted to systematize the F1-layer storm effects analyzing Ne(h) profiles obtained from the ionogram reduction over some European ionosonde stations. The analysis revealed two interesting effects: (i) independently of the sign of the F2-layer disturbance (positive or negative), the F1-layer electron concentration always decreases (negative storm effect), (ii) there exists a summer/winter and autumn/spring asymmetry in the F1-layer geomagnetic storm effects.…”

Section: Introductionmentioning

confidence: 99%

Geomagnetic storm effects at F1-layer heights from incoherent scatter observations

Mikhailov

Schlegel

2003

Ann. Geophys.

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Abstract. Storm effects at F1-layer heights (160-200 km) were analyzed for the first time using Millstone Hill (midlatitudes) and EISCAT (auroral zone) incoherent scatter (IS) observations. The morphological study has shown both increases (positive effect) and decreases (negative effect) in electron concentration. Negative storm effects prevail for all seasons and show a larger magnitude than positive ones, the magnitude of the effect normally increasing with height. At Millstone Hill the summer storm effects are small compared to other seasons, but they are well detectable. At EISCAT this summer decrease takes place only with respect to the autumnal period and the autumn/spring asymmetry in the storm effects is well pronounced. Direct and significant correlation exists between deviations in electron concentration at the F1-layer heights and in the F2-layer maximum. Unlike the F2-layer the F1-region demonstrates a relatively small reaction to geomagnetic disturbances despite large perturbations in thermospheric parameters. Aeronomic parameters extracted from IS observations are used to explain the revealed morphology. A competition between atomic and molecular ion contributions to N e variations was found to be the main physical mechanism controlling the F1-layer storm effect. The revealed morphology is shown to be related with neutral composition (O, O 2 , N 2 ) seasonal and storm-time variations. The present day understanding of the F1-region formation mechanisms is sufficient to explain the observed storm effects.

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“…Firstly, a priori, it is not obvious as F1-layer exhibits a small sensitivity to geomagnetic activity (Buresova and Laštovička, 2001;Buresova et al, 2002) resulting from its formation mechanism (Mikhailov and Schlegel, 2003). Secondly, problems with the foF1 identification from the ground-based ionosonde observations (Shchepkin and Vinitzky, 1981) and a poor quality of routine foF1 data may turn out to be an additional obstacle on this way.…”

Section: Introductionmentioning

confidence: 99%

Ionospheric F1 layer long-term trends and the geomagnetic control concept

Mikhailov

2008

Ann. Geophys.

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Abstract.A previous approach to the ionospheric long-term trend analysis has been applied to the foF1 observations from Slough and Rome in order to investigate a possible relationship between the foF1 and the long-term variation of geomagnetic activity. A 40-year period, starting in 1962, has been used for the analysis. According to the results obtained earlier for F2 and E-region trends, geomagnetic control of the long-term variation has also been revealed for the foF1. Thus, it is now possible to speak about the geomagnetic control of the ionospheric trends in the whole ionosphere. This is not surprising as the Earth's ionosphere is a single entity that is strongly controlled, either directly or indirectly, by the magnetic field. As with the F2-region, this geomagnetic control is provided via neutral composition and temperature changes. A very long-term (centennial) increase in geomagnetic activity in the 20th century is seen in the long-term foF1 variations as well. After its removal, the residual foF1 trends are very small and insignificant. In principal, this means that the observed foF1 long-term variations have a natural origin and can be attributed to solar and geomagnetic activity longterm variations. However, the situation in the thermosphere has been changing since 1997 and available foF2 observations at the two stations reveal information about the "break down" of the geomagnetic control in the F2-region. Possible reasons of these changes are discussed.

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Daytime electron density at the F1-region in Europe during geomagnetic storms

Cited by 30 publications

References 19 publications

Observation of the ionospheric storm of October 11, 2008 using FORMOSAT-3/COSMIC data

Observation of the ionospheric storm of October 11, 2008 using FORMOSAT-3/COSMIC data

Geomagnetic storm effects at F1-layer heights from incoherent scatter observations

Ionospheric F1 layer long-term trends and the geomagnetic control concept

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