Equatorial <i>E</i> region electric fields at the dip equator: 2. Seasonal variabilities and effects over Brazil due to the secular variation of the magnetic equator

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

doi:10.1002/2016ja022753

Cited by 12 publications

(26 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Resende et al () studied the competition between tidal winds and electric fields in the formation of Es b over SLZ. The authors reported an increase in the occurrence rates of Es b since 2009, revealing that the EEJ has little or no influence there, confirming the results of Tsunoda () about the anticorrelation characteristics between Es b and the EEJ intensity and Moro et al () about the secular variation of the geomagnetic field on the EEJ in terms of electric fields over SLZ.…”

Section: Introductionsupporting

confidence: 68%

“…However, the electric field components presented an interesting dependence with the dip equator secular displacement effect at SLZ (see Figure 1 in Moro et al, 2016a), which causes different variations in E y and E z at JRO. This result led to a study on the seasonal dependence of E y and E z by Moro et al (2016b), which revealed for the first time the impact of the secular variation of the geomagnetic field on the EEJ in terms of electric fields.…”

Section: Introductionmentioning

confidence: 98%

“…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%

See 2 more Smart Citations

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

et al. 2017

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our analysis, São Luís was still under the magnetic equator influence in 2005 and 2009, and thus two mechanisms can compete, neutral winds and electric fields, which are the responsible for the Es b layers formation or disruption. The secular variation on the geomagnetic field and its effect on the EEJ over Brazil is investigated by Moro et al (2016c).…”

Section: Discussionmentioning

confidence: 99%

Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

Resende

Batista

Denardini

et al. 2016

Earth Planets Space

View full text Add to dashboard Cite

In the present work, we analyze the competition between tidal winds and electric fields in the formation of blanketing sporadic E layers (Es b ) over São Luís, Brazil (2° 31′ S, 44° 16′ W), a quasi-equatorial station. To investigate this competition, we have used an ionospheric E region model (MIRE) that is able to model the Es b layers taking into account the E region winds and electric fields. The model calculates the densities for the main molecular and metallic ions by solving the continuity and momentum equations for each of the species. Thus, the main purpose of this analysis is to verify the electric fields role in the occurrence or disruption of Es b layers through simulations. The first results of the simulations show that the Es b layer is usually present when only the tidal winds were considered. In addition, when the zonal component of the electric field is introduced in the simulation, the Es b layers do not show significant changes. However, the simulations show the disruption of the Es b layers when the vertical electric field is included. In this study, we present two specific cases in which Es b layers appear during some hours over São Luís. We can see that these layers appear when the vertical electric field was weak, which means that the tidal components were more effective during these hours. Therefore, the vertical component of the electric field is the main agent responsible for the Es b layer disruption. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

show abstract

“…Therefore, there exists a gap in proper understanding the ionospheric variability in South America, especially in the Brazilian sector where there are some unique geophysical characteristics. One of them is the high magnetic declination angle that reaches approximately −20° in the equatorial region due to the dip equator secular displacement effect causing considerable changes in the Equatorial Electrojet and consequently in sporadic E (Es) layers (Denardini et al, ; Moro et al, , ; Moro et al, ; Resende et al, ). There is also a more pronounced energetic particle precipitation in the SAMA region (Moro et al, , ) when compared with other regions having the same latitudinal range, due to the global minimum in the intensity of the geomagnetic field.…”

Section: Introductionmentioning

confidence: 99%

On the Sources of the Ionospheric Variability in the South American Magnetic Anomaly During Solar Minimum

Moro

Xu²,

Denardini

et al. 2019

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

We investigate for the first time the variability of the F2 layer critical frequency (foF2), its peak height (hmF2), the thickness parameter B0, and the E region critical frequency (foE) over Santa Maria (29.7° S, 53.7° W, dip angle = −37°), a station located in the central region of the South American Magnetic Anomaly. The selected ionospheric parameters were obtained from ionograms recorded by a recent Digisonde Portable Sounder 4‐D. The time period covers 309 days from 1 September 2017 to 30 August 2018. The diurnal analyses revealed a large day‐to‐day ionospheric variability, with some peculiarities as a strong semiannual pattern superimposed to expected ionospheric behavior. Furthermore, the results show significant differences between the averaged foF2 in December and June solstices, revealing a possible presence of the annual asymmetry. The coefficient of variation (CV) is used as a quantitative description of the variability of each parameter versus time and season. Considering low solar flux and geomagnetically quiet days only, we note that CV is smaller during the daytime and larger during nighttime for all parameters. The least variable ionospheric parameter in our study is foE, while the most variable one is B0. Regarding the F2 layer parameters, we observe that foF2 is much more variable than hmF2. We attribute the observed CV to the neutral atmosphere source over Santa Maria. The ionospheric variability is in general enhanced during geomagnetically disturbed periods. The estimated CV is higher over Santa Maria than Wuhan, China (30.5° N, 114.4° E, dip angle = 46°), a station with no influence of the South American Magnetic Anomaly.

show abstract

Equatorial E region electric fields at the dip equator: 2. Seasonal variabilities and effects over Brazil due to the secular variation of the magnetic equator

Cited by 12 publications

References 49 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

Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

On the Sources of the Ionospheric Variability in the South American Magnetic Anomaly During Solar Minimum

Contact Info

Product

Resources

About