Variabilities of the equatorial electrojet in Brazil and Perú

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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“…In addition, Shume et al . [, ] and Guizelli et al . [] investigated the regional differences about the EEJ in the Brazilian and Peruvian sector.…”

Section: Introductionmentioning

confidence: 99%

E region electric field dependence of the solar activity

et al. 2015

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“…In Jicamarca the declination is almost zero, and São Luís is around 12S. A possible influence of the large negative declination angles over Brazil should be considered as one of the responsible by the stronger TEC over São Luís, once that the declination angle is supposed to be the causative of the modifications in the equatorial electrojet (Shume et al, 2010) and the EEJ is the main responsible by the daytime vertical drift.…”

Section: Discussionmentioning

confidence: 99%

Longitudinal variation of equatorial spread F occurrence over South America

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Valladares

Paula

et al. 2011

12th International Congress of the Brazilian Geophysical Society &Amp; EXPOGEF, Rio De Janeiro, Brazil, 15–18 August 2011

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“…In this section, we formally describe the wavelet analysis technique (readers who are familiar with this subject may wish to continue to section 3). A wavelet analysis decomposes a signal into a 2‐D time‐frequency image, thereby allowing the identification of physically important modes of variability in the signal as well as the determination of how these modes vary temporally [ Torrence and Compo , ; Shume et al , ]. Wavelet analysis is often applied for the purpose of spectral analysis of nonstationary signals [e.g., Wernik , ; Torrence and Compo , ] where the scintillation signal

{scriptS}_{4}

is an example.…”

Section: Data Sources and Analysis Techniquesmentioning

confidence: 99%

Flux tube analysis of L‐band ionospheric scintillation

et al. 2013

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[1] This manuscript presents magnetic flux tube analysis of L-band signal scintillation in the nighttime equatorial and low-latitude ionosphere. Residues of the scintillation index S 4 estimated from the L-band signals received from Geostationary Earth Orbit (GEO) satellites are employed in the analysis. The S 4 estimates have been shown to be associated with simultaneous GPS VTEC variations derived from JPL's GIPSY-GIM package. We have applied the wavelet decomposition technique simultaneously on the S 4 time series in a flux tube over the equatorial and low-latitude regions. The technique decomposes the S 4 signal to identify the dominant mode of variabilities and the temporal variations of scintillation-producing irregularities in the context of a flux tube. Statistically significant regions of the wavelet power spectra considered in our study have mainly shown that (a) dominant plasma irregularities associated with S 4 variabilities in a flux tube have periods of about 4 to 15 minutes (horizontal irregularity scales of about 24 to 90 km). These periods match short period gravity waves, (b) scintillation-producing irregularities are anisotropic along the flux tube and in the east-west direction, and (c) the occurrences of scintillation-producing irregularities along the flux tube indicate that the entire flux tube became unstable. However, plasma instability occurrences were not simultaneous in most cases along the flux tube, there were time delays of various orders. Understanding the attributes of L-band scintillation-producing irregularities could be important for developing measures to mitigate L-band signal degradation.

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Variabilities of the equatorial electrojet in Brazil and Perú

Cited by 27 publications

References 44 publications

E region electric field dependence of the solar activity

E region electric field dependence of the solar activity

Longitudinal variation of equatorial spread F occurrence over South America

Flux tube analysis of L‐band ionospheric scintillation

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