<i>E</i> region electric field dependence of the solar activity

Denardini, Clezio Marcos; Moro, Juliano; Resende, L. C. A.; Chen, Sony Su; Schuch, Nelson Jorge; Costa, J. E. R.

doi:10.1002/2015ja021714

Cited by 9 publications

(20 citation statements)

References 42 publications

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“…The steady northwestward excursions of the geomagnetic field strongly influence the electrodynamics of the E region plasma over the eastern Brazilian region. The features of the EEF and, consequently, the EEJ and E s are strongly affected and have been studied by many researches using data from radars, ionosondes, magnetometers, and computing modeling (Abdu et al, 1996;Abdu, Bittencourt, & Batista, 1981;Batista, Abdu, & Bittencourt, 1986;Batista et al, 2011;Denardini et al, 2013Denardini et al, , 2015Moro et al, 2016aMoro et al, , 2016bResende et al, 2016Resende et al, , 2017. The ionograms collected in SLZ show the presence of Es q and Es b layers.…”

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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“…The results presented above were briefly discussed in Denardini et al (2015) in terms of the simultaneous underestimation and overestimation of the variables provided by the MSIS, IRI, and IGRF models. Now, we focus the discussions in terms of the individual contributions of eventual underestimations and overestimations in the empirical models as well as simultaneous underestimations or overestimations in two out of three models.…”

Section: Discussionmentioning

confidence: 99%

“…The ranges of radar heights used in this work are as follows: from 101.3 to 103.9 km, centered at 102.5 km; from 103.9 to 106.5 km, centered at 105.1 km; from 106.5 to 109.1 km, centered at 107.7 km; and from 109.1 to 111.7 km, centered at 110.3 km. A detailed description of the RESCO and examples of observations are given by Abdu et al (2002) and Denardini et al (2004Denardini et al ( , 2005Denardini et al ( , 2006Denardini et al ( , 2009Denardini et al ( , 2015.…”

Section: Resco Radar Operational Parametersmentioning

confidence: 99%

“…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%

“…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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Equatorial E region electric fields at the dip equator: 1. Variabilities in eastern Brazil and Peru

et al. 2016

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The equatorial electrojet (EEJ) is an intense eastward ionospheric electric current centered at about 105 km of altitude along the dip equator, set up by the global neutral wind dynamo that generates the eastward zonal (Ey) and the daytime vertical (Ez) electric fields. The temporal variation of the EEJ is believed to be well understood. However, the longitudinal variability of the Ey and Ez between 100 and 110 km is still quite scarce. Due to their importance overall phenomenology of the equatorial ionosphere, we investigate the variabilities of the Ey and Ez inferred from measurements of the Doppler frequency of Type II echoes provided by coherent backscatter radars installed in locations close to the magnetic equator in the eastern Brazil (2.33°S, 44.20°W) and Peru (11.95°S, 76.87°W). This study is based on long‐term (609 days for both systems) radar soundings collected from 2001 to 2010. The variabilities of the electric fields are studied in terms of the position of the soundings with respect to the dip equator and the magnetic declination angle. Among the results, Ey and Ez show longitudinal dependence, being higher in Peru than east Brazil. Under quiet geomagnetic activity, the mean diurnal variations of Ey ranged from 0.21 to 0.35 mV/m between 8 and 18 h (LT) in Brazil and from 0.23 mV/m to 0.45 mV/m in Peru, while the mean diurnal variations of the Ez ranges from 7.09 to 8.80 mV/m in Brazil and from 9.00 to 11.18 mV/m in Peru.

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E region electric field dependence of the solar activity

Cited by 9 publications

References 42 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

Equatorial E region electric fields at the dip equator: 1. Variabilities in eastern Brazil and Peru

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