Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

Abstract

Scintillation due to ionospheric plasma irregularities remains a challenging task for the space science community as it can severely threaten the dynamic systems relying on space-based navigation services. In the present paper, we probe the ionospheric current and plasma irregularity characteristics from a latitudinal arrangement of magnetometers and Global Navigation Satellite System (GNSS) stations from the equator to the far low latitude location over the Indian longitudes, during the severe space weather events of 6–10 September 2017 that are associated with the strongest and consecutive solar flares in the 24th solar cycle. The night-time influence of partial ring current signatures in ASYH and the daytime influence of the disturbances in the ionospheric E region electric currents (Diono) are highlighted during the event. The total electron content (TEC) from the latitudinal GNSS observables indicate a perturbed equatorial ionization anomaly (EIA) condition on 7 September, due to a sequence of M-class solar flares and associated prompt penetration electric fields (PPEFs), whereas the suppressed EIA on 8 September with an inverted equatorial electrojet (EEJ) suggests the driving disturbance dynamo electric current (Ddyn) corresponding to disturbance dynamo electric fields (DDEFs) penetration in the E region and additional contributions from the plausible storm-time compositional changes (O/N2) in the F-region. The concurrent analysis of the Diono and EEJ strengths help in identifying the pre-reversal effect (PRE) condition to seed the development of equatorial plasma bubbles (EPBs) during the local evening sector on the storm day. The severity of ionospheric irregularities at different latitudes is revealed from the occurrence rate of the rate of change of TEC index (ROTI) variations. Further, the investigations of the hourly maximum absolute error (MAE) and root mean square error (RMSE) of ROTI from the reference quiet days’ levels and the timestamps of ROTI peak magnitudes substantiate the severity, latitudinal time lag in the peak of irregularity, and poleward expansion of EPBs and associated scintillations. The key findings from this study strengthen the understanding of evolution and the drifting characteristics of plasma irregularities over the Indian low latitudes.

TEC disturbances caused by CME-triggered geomagnetic storm of September 6–9, 2017

“… [21] mentioned that PPE field and composition caused TEC enhancement in low latitude region and it was absent in the equatorial region. These results are also supported by [52] and [26] . The combined impacts of IMF orientation, geomagnetic latitude dependency, and ionospheric response characteristics may cause the values of PPEF to decline more over high latitude stations during geomagnetic storms than over low and middle-latitude stations [66] , [67] .…”

“…The model uses time and longitude of the station as input factors to obtain the best estimations of the equatorial electric field. The model outputs show the electric field produced by the convective electric field, the quiet time electric field, and a combination of the two [50] , [51] , [52] . We use the Ionospheric Electric Fields Real-time Model data obtained from the website ( https://geomag.colorado.edu/real-time-model-of-the-ionospheric-electric-fields ).…”

Ionospheric–Thermospheric Responses to Geomagnetic Storms from Multi-Instrument Space Weather Data

“…The PPEF and D iono were the main reasons behind these fluctuations in the November 2021 storm. In fact, Fuller-Rowell et al [46], Mannucci et al [7], and Vankadara et al [49] presented similar results. The PPEF plays a vital role in vTEC enhancements through plasma diffusion along magnetic field lines, thus creating the fountain effect during the daytime [7].…”

“…The anti-Sq signatures observed during the recovery phase in the magnetic data are due to the orientation of electric fields [58]. Vankadara et al [49] performed a similar study, showing Dion minima at different Local Solar Time (LST) locations, leading to equatorial plasma bubble developments. Our results have shown differences in longitude because of magnetospheric convection processes and electric field penetration [59].…”

Multi-instrumental analysis of the day-to-day variability of equatorial plasma bubbles

“…Equatorial plasma bubbles (EPBs) are irregular plasma density depletion structures that are often observed at the nighttime equatorial and low-latitude ionospheric F-region, which have continued to be of long-standing research interest for decades due to their adverse impacts on navigation, communication, and radar systems (Hysell, 2000). The morphological features and dynamic variations of EPBs and associated plasma irregularities have been widely studied using a variety of ground-based and space-borne instruments/measurements, such as ionosonde (e.g., Booker and Wells, 1938;Cohen and Bowles, 1961;Abdu et al, 1982), coherent and incoherent scatter radars (e.g., Woodman and La Hoz, 1976;Hysell and Burcham, 2002;Jin et al, 2018;Rodrigues et al, 2018), all-sky airglow imagers (e.g., Mendillo and Baumgardner, 1982;Otsuka et al, 2002;Makela and Kelley, 2003;Martinis et al, 2015), space-based ultraviolet imagers (e.g., Kil et al, 2004;Aa et al, 2020a;Eastes et al, 2020;Karan et al, 2020), low-Earth orbiting satellites in-situ measurements (e.g., Burke et al, 2004;Stolle et al, 2006;Huang et al, 2012;Xiong et al, 2016;Aa et al, 2020b), as well as Global Navigation Satellite System (GNSS) total electron content (TEC) or scintillation observations (e.g., Valladares and Chau, 2012;Takahashi et al, 2015;Cherniak and Zakharenkova, 2016;Zakharenkova et al, 2016;Aa et al, 2018;Aa et al, 2019;Alfonsi et al, 2021;Vankadara et al, 2022). In addition, numerical simulations have also been utilized to analyze the onset condition and evolution process of EPBs (e.g., Retterer et al, 2005;Huba et al, ...…”