E region electric fields at the dip equator and anomalous conductivity effects

Denardini, Clezio Marcos; Aveiro, H. C.; Sobral, J. H. A.; Bageston, José Valentin; Guizelli, L. M.; Resende, L. C. A.; Moro, Juliano

doi:10.1016/j.asr.2012.06.003

Cited by 9 publications

(21 citation statements)

References 53 publications

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“…The equatorial electrojet (EEJ) consists of a small Pedersen current driven by the zonal ( E y ) electric field generated by tidal neutral winds and a large Hall current driven by the vertical ( E z ) polarization electric field. The E z component, in turn, is produced by an impeded Hall current driven by the primary E y (Denardini et al, ; Forbes, ; Moro et al, , and references therein). The E y component, eastward during the daytime, controls the vertical plasma transport in the low‐latitude ionosphere and forms a critical input to models that predict ionospheric disturbances in real time (Maruyama et al, ; Scherliess et al, ).…”

Section: Introductionmentioning

confidence: 99%

Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

et al. 2017

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Equatorial E region electric fields (EEFs) inferred from coherent radar data, sporadic‐E (Es) layers observed from a digital ionosonde data, and modeling results are used to study the responses of the equatorial E region over São Luís (SLZ, 2.3°S, 44.2°W, ~−7° dip angle), Brazil, during the super storm of November 2004. The EEF is presented in terms of the zonal (Ey) and vertical (Ez) components in order to analyze the corresponding characteristics of different types of Es seen in ionograms and simulated with the E region ionospheric model. We bring out the variabilities of Ey and Ez components with storm time changes in the equatorial E region. In addition, some aspects of the electric fields and Es behavior in three cases of weak, very weak, and strong Type II occurrences during the recovery phase of the geomagnetic storm are discussed. The connection between the enhanced occurrence and suppressions of the Type II irregularities and the q‐type Es (Esq) controlled by electric fields, with the development or disruption of the blanketing sporadic E (Esb) layers produced by wind shear mechanism, is also presented. The mutual presence of Esq along with the Esb occurrences is a clear indicator of the secular drift of the magnetic equator and hence that of the equatorial electrojet (EEJ) over SLZ. The results show evidence about the EEJ and Es layer electrodynamics and coupling during geomagnetic disturbance time electric fields.

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Section: Introductionmentioning

confidence: 99%

Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

et al. 2017

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“…SUPIM has been developed over the last three decades and includes numerous physical and chemical processes of the Earth's mid-and lowlatitude ionosphere and plasmasphere (Bailey et al 1997). The set of collision frequencies presented in Table 1 was also used to infer the E-region electric fields by Denardini et al (2013Denardini et al ( , 2015. The neutral densities of O, O 2 , and N 2 are represented by n(O), n(O 2 ), and n(N 2 ), respectively.…”

Section: Magnetic Field-line-integrated Ionospheric Conductivity Modelmentioning

confidence: 99%

“…The model offered results consistent with the conductivity model developed by the Kyoto University. Later, this model was extended (version 2009) to include several ionic and neutral species by Denardini et al (2013). A new set of ion-neutral and electron-neutral collision frequencies was included, and the momentum transfer collision frequency equation was used to balance these rates (Bailey and Balan 1996;Schunk and Nagy 2004).…”

Section: Magnetic Field-line-integrated Ionospheric Conductivity Modelmentioning

confidence: 99%

“…Ionospheric electric fields and their time variations play a dominant role in the ionospheric electrodynamic at low latitudes, especially during daytime at the E-region height in the low-latitude ionosphere (Denardini et al 2013). The basic global mechanism that generates these electric fields in the ionosphere is known to be the global dynamo action of neutral winds.…”

Section: Introductionmentioning

confidence: 99%

“…Such monitoring leads to a clearer understanding of the EEJ, E-and F-region irregularities, pre-reversal vertical drift (eastward electric field enhancement), spread-F, and Appleton anomaly. Consequently, the ionospheric electric fields have widely been studied using radars, magnetometers, ionosondes, and satellites for many years (see, for example, Woodman 1972;Singh and Cole 1987;Crain et al 1993;Fejer and Scherliess 1997;Hysell and Burcham 2000;Fejer et al 2008;Aveiro et al 2009a, b;Denardini et al 2009Denardini et al , 2011Denardini et al , 2013Denardini et al , 2015.…”

Section: Introductionmentioning

confidence: 99%

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Influence of uncertainties of the empirical models for inferring the E-region electric fields at the dip equator

et al. 2016

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Daytime E-region electric fields play a crucial role in the ionospheric dynamics at the geomagnetic dip latitudes. Due to their importance, there is an interest in accurately measuring and modeling the electric fields for both climatological and near real-time studies. In this work, we present the daytime vertical (Ez) and eastward (Ey) electric fields for a reference quiet day (February 7, 2001) at the São Luís Space Observatory, Brazil (SLZ, 2.31°S, 44.16°W). The component Ez is inferred from Doppler shifts of type II echoes (gradient drift instability) and the anisotropic factor, which is computed from ion and electron gyro frequencies as well as ion and electron collision frequencies with neutral molecules. The component Ey depends on the ratio of Hall and Pedersen conductivities and Ez. A magnetic field-line-integrated conductivity model is used to obtain the anisotropic factor for calculating Ez and the ionospheric conductivities for calculating Ey. This model uses the NRLMSISE-00, IRI-2007, and IGRF-11 empirical models as input parameters for neutral atmosphere, ionosphere, and geomagnetic field, respectively. Consequently, it is worth determining the uncertainties (or errors) in Ey and Ez associated with these empirical model outputs in order to precisely define the confidence limit for the estimated electric field components. For this purpose, errors of ±10 % were artificially introduced in the magnitude of each empirical model output before estimating Ey and Ez. The corresponding uncertainties in the ionospheric conductivity and electric field are evaluated considering the individual and cumulative contribution of the artificial errors. The results show that the neutral densities and temperature may be responsible for the largest changes in Ey and Ez, followed by changes in the geomagnetic field intensity and electron and ions compositions.

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E region electric field dependence of the solar activity

et al. 2015

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We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent radar set at São Luis, Brazil (SLZ, 2.3°S, 44.2°W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp ≤ 3+). A magnetic field‐aligned‐integrated conductivity model was developed for proving the conductivities, using the IRI‐2007, the MISIS‐2000, and the IGRF‐11 models as input parameters for ionosphere, neutral atmosphere, and Earth magnetic field, respectively. The ion‐neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlights the more pronounced dependency of the solar flux.

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E region electric fields at the dip equator and anomalous conductivity effects

Cited by 9 publications

References 53 publications

Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

Influence of uncertainties of the empirical models for inferring the E-region electric fields at the dip equator

E region electric field dependence of the solar activity

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