Performance of the IRI-2016 over Santa Maria, a Brazilian low-latitude station located in the central region of the South American Magnetic Anomaly (SAMA)

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Santa Maria Digisonde data are used for the first time to investigate the F region behavior during a geomagnetic storm. The August 25, 2018 storm is considered complex due to the incidence of two Interplanetary Coronal Mass Ejections and a High‐Speed Solar Wind Stream (HSS). The F 2 layer critical frequency (f o F 2) and its peak height (h m F 2) collected over Santa Maria, near the center of the South American Magnetic Anomaly (SAMA), are compared with data collected from Digisondes installed in the Northern (NH) and Southern (SH) Hemispheres in the American sector. The deviation of f o F 2 (Df o F 2) and h m F 2 (Dh m F 2) are used to quantify the ionospheric storm effects. Different F region responses were observed during the main phase (August 25–26), which is attributed to the traveling ionospheric disturbances and disturbed eastward electric field during nighttime. The F region responses became highly asymmetric between the NH and SH at the early recovery phase (RP, August 26) due to a combination of physical mechanisms. The observed asymmetries are interpreted as caused by modifications in the thermospheric composition and a rapid electrodynamic mechanism. The persistent enhanced thermospheric [O]/[N2] ratio observed from August 27 to 29 combined with the increased solar wind speed induced by the HSS and IMF B z fluctuations seem to be effective in causing the positive ionospheric storm effects and the shift of the Equatorial Ionization Anomaly crest to higher than typical latitudes. Consequently, the most dramatic positive ionospheric storm during the RP occurred over Santa Maria (∼120%).

Section: Data Presentation and Methods Of Analysismentioning

confidence: 99%

First Look at a Geomagnetic Storm With Santa Maria Digisonde Data: F Region Responses and Comparisons Over the American Sector

Moro

Xu²,

Denardini

et al. 2021

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“…More details about the Santa Maria Digisonde including the past studies about the variability of the E ‐region and F ‐region parameters, and its comparisons with the International Reference Ionosphere (IRI) model during geomagnetic quiet days can be found in Moro et al. (2019, 2020, 2021). The present work is the first one about the Es layers responses over Santa Maria.…”

Section: Data and Modelmentioning

confidence: 99%

“…The SMK29 data are automatically uploaded to the Embrace website and the Digisonde network of the Global Ionosphere Radio Observatory (GIRO) Digital Ionogram DataBase (DIDBase; Reinisch & Galkin, 2011). More details about the Santa Maria Digisonde including the past studies about the variability of the E-region and F-region parameters, and its comparisons with the International Reference Ionosphere (IRI) model during geomagnetic quiet days can be found in Moro et al (2019Moro et al ( , 2020Moro et al ( , 2021. The Es layer parameters used in this work are manually scaled from the ionograms with the SAO Explorer software according to the echo's traces.…”

Section: Instrumentationmentioning

confidence: 99%

Different Sporadic‐E (Es) Layer Types Development During the August 2018 Geomagnetic Storm: Evidence of Auroral Type (Es_a) Over the SAMA Region

Moro

Nardin

et al. 2022

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The solar activity phenomena that originate the nonrecurrent geomagnetic storms involve sudden explosions of nonpotential magnetic field lines in active regions, which may or may not be accompanied by solar flares, and eruptive filaments outside the active regions (Abunin et al., 2020;Belov et al., 2014;Chen et al., 2019). One remarkable example of a nonrecurrent geomagnetic storm occurred in August 2018, the third strongest of the Solar Cycle 24. The complex space weather responses were generated by two interplanetary coronal mass ejections (ICME) and by the High-Speed Solar Wind Stream (HSS) that hit the Earth between 25 and 27 August 2018.In general, the disturbed magnetospheric electric fields cause large modifications in the ionosphere dynamics during geomagnetic storms. Several works have improved the understanding of these disturbed electric fields showing that they promptly penetrate to the equatorial latitudes oriented in dawn-to-dusk direction as soon as the interplanetary magnetic field (IMF) B z component turns southward, initiating a substorm, which, in turn, increase the activity of auroral electrojet (

“…Closer to the dip equator, for instance, IPPs located at higher altitudes can be more wellsuited (e.g., Espejo et al, 2022). The stations used in this work, however, are located at low-to-mid latitudes and both, simulations (Souza et al, 2000) and observations (Moro et al, 2020) indicate that, over these latitudes, the F-region peak is commonly located around 350 km.…”

Section: On the Spatio-temporal Evolution Of Scintillations At Geomag...mentioning

confidence: 86%

First Observations of Severe Scintillation Over Low‐to‐Mid Latitudes Driven by Quiet‐Time Extreme Equatorial Plasma Bubbles: Conjugate Measurements Enabled by Citizen Science Initiatives

Sousasantos,

Rodrigues,

Gomez Socola

et al. 2024

Low‐cost instrumentation combined with volunteering and citizen science educational initiatives allowed the deployment of L‐band scintillation monitors to remote sense areas that are geomagnetically conjugated and located at low‐to‐mid latitudes in the American sector (Quebradillas in Puerto Rico and Santa Maria in Brazil). On 10 and 11 October, 2023, both monitors detected severe scintillations, some reaching dip latitudes beyond 26°N. The observations show conjugacy in the spatio‐temporal evolution of the scintillation‐causing irregularities. With the aid of collocated all‐sky airglow imager observations, it was shown that the observed scintillation event was caused by extreme equatorial plasma bubbles (EPBs) reaching geomagnetic apex altitudes exceeding 2,200 km. The observations suggest that geomagnetic conjugate large‐scale structures produced conditions for the development of intermediate scale (few 100 s of meters) in both hemispheres, leading to scintillation at conjugate locations. Finally, unlike previous reports, it is shown that the extreme EPBs‐driven scintillation reported here developed under geomagnetically quiet conditions.