The Impact of the Disturbed Electric Field in the Sporadic E (Es) Layer Development Over Brazilian Region

Abstract

During disturbed periods, E region electric fields can cause anomalous Es layer behavior, which is observed in the digital ionosonde data. To investigate the influence of these electric fields in the Es layer development, we analyzed a set of 20 magnetic storms from 2015 to 2018 over Boa Vista (BV, 2.8°N, 60.7°W, dip ∼18°), São Luís (SLZ, 2.3°S, 44.2°W, dip ∼8°), and Cachoeira Paulista (CXP, 22.41°S, 45°W, dip ∼35°). The electric field zonal components during the main and recovery phases of each magnetic storm are computed to study the corresponding characteristics of these Es seen in ionograms. Additionally, a numerical model (MIRE, Portuguese acronym for E Region Ionospheric Model) is used to analyze the Es layer dynamics modification around disturbed times. Using observation data and simulations, we were able to establish a threshold value for the electric field intensity for each region that can affect the Es layer formation. The results sustain that the strong Es layer in BV can be an indicator of the disturbed dynamo event. At SLZ, on the other hand, the Es layers are affected by the competition mechanisms of their formation, as equatorial electrojet irregularities and winds, during the main phase of the magnetic storm. Over CXP, the Es layer dynamics are dominated by the wind shear mechanism. Finally, this study provides new insights into the real impact of the electric field in the Es layer development over the Brazilian sector. Thus, our results lead to a better understanding of the underlying mechanisms related to the Es layer formation and dynamics.

New Findings Relating Tidal Variability and Solar Activity in the Low Latitude MLT Region

“…Es layer occurrences in Cachoeira Paulista have being studied for decades (e.g., but this is the first time the difference in Es occurrences between minimum and maximum solar cycle activity is presented. In a more recent work, Resende et al (2021) showed that over this site, the Es layer dynamics are dominated by the wind shear mechanism, not being influenced by the electric field. Hence, the anticorrelation seen in the frequency of the Es layer is probably a consequence of the impact of solar activity in tidal winds.…”

“…In a more recent work, Resende et al. (2021) showed that over this site, the Es layer dynamics are dominated by the wind shear mechanism, not being influenced by the electric field. Hence, the anticorrelation seen in the frequency of the Es layer is probably a consequence of the impact of solar activity in tidal winds.…”

“…Recently, Resende et al. (2021) analyzed a set of 20 magnetic storms from 2015 to 2018 in different Brazilian regions, to observe the physical mechanisms in the Es layer formation. The authors used data from Boa Vista (BV, 2.8°N, 60.7°W, dip ∼18°), São Luís (SLZ, 2.3°S, 44.2°W, dip ∼8°), and CP (dip ∼35°).…”

“…Over the Brazilian sector, Resende et al (2017aResende et al ( , 2017b) used the MIRE model (MIRE, Portuguese acronym for E Region Ionospheric Model) and observational data to show that the main contribution in forming these Es is the tidal winds shear mechanism. Recently, Resende et al (2021) analyzed a set of 20 magnetic storms from 2015 to 2018 in different Brazilian regions, to observe the physical mechanisms in the Es layer formation. The authors used data from Boa Vista (BV, 2.8°N, 60.7°W, dip ∼18°), São Luís (SLZ, 2.3°S, 44.2°W, dip ∼8°), and CP (dip ∼35°).…”

“…Furthermore, much of the inter-annual variability in mean and tidal winds remains unexplained at present. Tidal winds have an important role in the development of Sporadic layers in the ionospheric E region across different regions of the globe (Luo et al, 2021;Resende et al, 2017aResende et al, , 2017bResende et al, , 2021. These layers are characterized by patches of enhanced electron density around 95-140 km in the ionosphere, composed mainly of metallic ions (Mathews & Bekeny, 1979;Whitehead, 1961).…”