Abstract
AbstractThis 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.
Highlights
Sporadic E (Es) layers are dense and thin layers, which are mainly formed by the wind shear mechanism in low/midlatitudes (Haldoupis, 2011; Mathews, 1998; Whitehead, 1961)
The ionospheric behavior on days around the magnetic storm that occurred on 20 January 2016 was investigated to search for possible explanations
We selected the magnetic storm that occurred on 20 January 2016 to perform a case study, searching for a possible explanation for the unexpected Es strengthening. It was analyzed the F region parameters combined with the total electron content (TEC) maps from the Global Navigation Satellite System (GNSS), indicating that a disturbance dynamo electric fields (DDEFs) event was the cause of the atypical Es layer
Summary
Sporadic E (Es) layers are dense and thin layers, which are mainly formed by the wind shear mechanism in low/midlatitudes (Haldoupis, 2011; Mathews, 1998; Whitehead, 1961). The results showed the occurrence of other Es layer types, mainly during the recovery phase of the magnetic storm, that is generally associated with wind shears The observation of these types of layers is more common at low latitudes/midlatitudes than at equatorial regions. We selected the magnetic storm that occurred on 20 January 2016 to perform a case study, searching for a possible explanation for the unexpected Es strengthening It was analyzed the F region parameters combined with the total electron content (TEC) maps from the Global Navigation Satellite System (GNSS), indicating that a DDEF event was the cause of the atypical Es layer.
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