Peculiar Magnetosphere-Atmosphere Coupling and Its Impacts Over the South American Magnetic Anomaly Region

Le résumé fourni par la source

The auroral-like sporadic E-layer is typically observed at altitudes between 100 and 150 km within the South American Magnetic Anomaly region. However, the occurrence of an unusual layer event detected above this altitude range on 18 July 2017 has raised intriguing questions regarding the physical processes responsible for the substantial vertical displacement of this layer. The interplanetary medium conditions during the event exhibited characteristics consistent with the recovery phase of a geomagnetic storm driven by a complex solar wind structure, occurring after substorm activity. To address this atypical layer occurrence, we examined the magnetospheric conditions using the BATS-R-US model with two experiments: one including the actual geomagnetic dipole inclination and another omitting it. These configurations allow for a discussion of the energy deposition processes under the prevailing interplanetary medium conditions. Also, the dynamics of the inner radiation belt were investigated through analysis of the magnetic field power spectral density and low-energy electron flux measurements from the Van Allen Probes mission to verify electron precipitation. Plasma wave observations and their characterization also revealed atypical behavior, in which a non-standard confinement of hiss waves (200 and 500 Hz) occurred simultaneously with an electron flux decrease (<1 keV), an integrated ionization rate between 250 and 300 km, and the formation of a peculiar layer. Finally, although this magnetic storm was moderate, we demonstrate that particle precipitation significantly impacted the atmosphere, as evidenced by pronounced ozone depletion in the mesosphere with magnitudes substantially stronger when compared to the extreme storm of May 2024.

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