The Influence of Disturbance Dynamo Electric Field in the Formation of Strong Sporadic E Layers Over Boa Vista, a Low‐Latitude Station in the American Sector

Abstract

This study analyzes strong sporadic E layer (Es) formation in Boa Vista (BV, 2.8°N, 60.7°W, dip: 18°), a low‐latitude region in the Brazilian sector, which occurred far after the onset of a magnetic storm recovery phase. Such occurrences were observed during seven magnetic storms with available data for BV. Thus, the ionospheric behavior on days around the magnetic storm that occurred on 20 January 2016 was investigated to search for possible explanations. This analysis indicated that the probable mechanism acting during the Es layer strengthening is the zonal westward electric field caused by a disturbance dynamo. The same evidence was also observed in two other magnetic storms at the same location. Hence, a numerical model of the E region dynamics, called MIRE (Portuguese acronym for E Region Ionospheric Model), was used to confirm whether the disturbance dynamo could cause the Es layer intensification. The inputs for the model were the electric field deduced from the vertical drift and the wind components provided by GSWM‐00 model. The simulations indicate that the Es layer density is significantly enhanced when the zonal electric field is present compared to the reference scenario with only the winds. Therefore, it is concluded that the disturbance dynamo electric field is the likely cause of the strong Es layers in the analyzed cases. Finally, the combined results from the model and observational data seem to contribute significantly to advance our understanding of the role of the electric fields in the Es layer formation at low latitudes.

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

“…In this analysis, the maximum computed drift velocity was considered when obtaining the electric field. Notice that we do not estimate the other electric field components because they do not significantly influence the Es layer dynamics over the analyzed regions (Abdu et al., 2014; Resende et al., 2020).…”

“…The parameters of the GSWM-00 are given by the High-Altitude Observatory of the National Center for Atmospheric Research in Colorado (http://www.hao.ucar.edu/ modeling/gswm/gswm.html). Resende et al (2020) implemented the GSWM-00 parameters in MIRE to analyze the Es layers in BV. In the present study, we extended a similar analysis for SLZ and CXP using the GSWM-00 already included in the MIRE model for the first time for these regions.…”

“…For instance, Abdu et al (2014) reported on intensification or disruption of the Es layers associated with the Hall electric field induced by the prompt penetration electric fields (PPEFs) at low latitudes. More recently, Resende et al (2020) detected strong Es layers in Boa Vista (BV, Geographic Coordinates: 2.8°N, 60.7°W, Magnetic Inclination: ∼18°), a station located near the geographic equator in the Brazilian sector, during the recovery phase of magnetic storms. They concluded that these anomalous Es layers are a consequence of the combined effect of the winds and disturbed electric fields.…”

A multi-instrumental and modelling analysis of the ionospheric responses to the solar eclipse of December 14, 2020, over the Brazilian region

“…We have used a theoretical model, called MIRE, which provides the E region and Es layer electron densities as follows (Carrasco et al, 2007;Resende et al 2017aResende et al , 2017bResende et al , 2020Resende et al , 2021:…”

“…The transport term depends on the wind and electric field parameters (Resende et al 2020). This analysis only considers the E-region chemistry, thus neglecting the transport terms and metallic ions.…”