Occurrence and Modeling Examination of Sporadic‐E Layers in the Region of the South America (Atlantic) Magnetic Anomaly

• Published in: Journal of geophysical research. Space physics 2019-11, Vol.124 (11), p.9676-9694
• Main Authors: Conceição‐Santos, Fredson, Muella, Marcio T. A. H., Resende, Laysa C. A., Fagundes, Paulo R., Andrioli, Vania F., Batista, Paulo P., Pillat, Valdir G., Carrasco, Alexander J.
• Format: Article
• Language: English
• Subjects: Blanketing; Computer simulation; E region; Electron density; Electrons; Energetic particles; E‐region model; Ionization; Ionosondes; Ionospheric models; Magnetic anomalies; Mathematical models; Meridional wind; meteor radar; Parameters; Particle precipitation; Planetary waves; Radar; Radar data; SAMA region; Sporadic E layer; Stations; Storms; Tidal winds; Wind; Wind components; Wind shear; Wind variability
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2018JA026397

In this work, the occurrence of different types of sporadic‐E layers (Es) was described for two stations located in the region of the South America Magnetic Anomaly: Jataí and São José dos Campos. The results show the hourly and monthly values of the Es occurrences and presented five types of layers (cusp, high, flat, low, and slant), with the flat/low types (Esf/l) being the most frequent over both stations. We also analyzed the Es layer parameters of blanketing frequency (fbEs) and top frequency (ftEs) obtained from ionosonde data during storm‐time periods, in order to investigate possible evidences of energetic particle‐induced E‐layer ionization. The results revealed increases in the values of the nighttime ftEs and fbEs, which can be related to the particle precipitation in the South America Magnetic Anomaly region. Additionally, we investigated the roles of the wind shear mechanism in the formation of the Es types by using a modified form of the Ionospheric E‐Region Model (MIRE), which incorporates tidal winds obtained from meteor radar data. Furthermore, the electron densities deduced from fbEs parameter were compared with the maximum electron densities obtained from MIRE simulations. Depending on local time and season, the initial results revealed for both stations some discrepancies between modeled and measured electron densities. However, a better fitting was obtained when the amplitudes of the zonal/meridional wind components were adjusted by some factor, which may be attributed to the possible effects of day‐to‐day tidal wind variability and their interaction with gravity and planetary waves. Key Points The flat/low Es are the most frequent types of sporadic layers observed at the low‐latitude stations Es frequency parameters during moderate storms showed evidences of energetic particle‐induced E‐layer ionization around the SAMA region Modeled and measured electron densities revealed the role of the wind shear mechanism in the formation of the observed Es layers