From the Sun to the Earth: August 25, 2018 geomagnetic storm effects

Abstract

<p>On August 25, 2018 the interplanetary counterpart of the August 20, 2018 Coronal Mass Ejection (CME) hit the Earth, giving rise to a strong geomagnetic storm. We present a description of the whole sequence of events from the Sun to the ground as well as a detailed analysis of the onserved effects on the Earth's environment by using a multi instrumental approach. <br>We studied the ICME propagation in the interplanetary space up to the analysis of its effects in the magnetosphere, ionosphere and at ground. To accomplish this task, we used ground and space collected data, including data from CSES (China Seismo Electric Satellite), launched on February 11, 2018. We found a direct connection between the ICME impact point onto the magnetopause and the pattern of the Earth's polar electrojects. Using the Tsyganenko TS04 model prevision, we were able to correctly identify the principal magnetospheric current system activating during the different phases of the geomagnetic storm. Moreover, we analyzed the space-weather effects associated with the August 25, 2018 solar event in terms of evaluation geomagnetically induced currents (GIC) and identification of possible GPS loss of lock. We found that, despite the strong geomagnetic storm, no loss of lock has been detected. On the contrary, the GIC hazard was found to be potentially more dangerous than other past, more powerful solar events, such as the St. Patrick geomagnetic storm, especially at latitudes higher than $60^\circ$ in the European sector.</p>

Solar Origins of August 26, 2018 Geomagnetic Storm: Responses of the Interplanetary Medium and Equatorial/Low‐Latitude Ionosphere to the Storm

“…This sequence of solar events is in agreement with the report of Piersanti et al. (2020). The weak solar wind energy got transferred into the magnetosphere to drive electrical currents, which propagated down into the ionosphere to also produce weak PPEF (0.3 mV/m).…”

“…Previously, Piersanti et al. (2020) provided a sequence of events from the Sun to the Earth during the period of this storm. However, in the aspect of ionospheric response to the storm, these authors provided limited analysis as they only considered SWARM data for August 25–27, 2018 at about 02:00 and 14:00 LT and ionospheric irregularities inferred from only SWARM PRN 17 RODI for only the main phase of the storm.…”

“…Consequently, although Piersanti et al. (2020) had earlier reported a whole sequence of events from the Sun to the Earth for this storm, however, new studies that will assist space weather community's understanding of the physical processes that led to the storm and the subsequent responses of the ionosphere to it (storm), particularly with a view to developing future space weather forecasting capabilities are required.…”

On the Magnetosphere‐Ionosphere Coupling During the May 2021 Geomagnetic Storm

“…As a closing comment, we want to highlight that despite the Sun is in general more active during its maximum and declining phases, recent papers showed the occurrence of extreme space weather events close to the solar activity minimum (Hayakawa et al., 2020; Hayakawa, Schlegel, et al., 2021; Piersanti et al., 2020). As a consequence, we remark that this kind of global analysis ‐ namely, the study of an ICME propagation from its source on the Sun across the magnetosphere‐ionosphere system to its impact in terms of magnetic field changes and magnetospheric particle redistribution, is still the straightforward way available to understand the complex dynamics of the processes occurring in the circumterrestrial environment from a space weather point of view.…”

“…They are extremely complicated processes, which are triggered by the arrival of solar perturbations, such as interplanetary coronal mass ejections (ICMEs), solar flares, co‐rotating interaction regions (CIRs), etc. (e.g., Gonzalez et al., 1994; Gosling et al., 1990; Knipp, Delores J. et al., 2021; Miyake et al., 2019; Piersanti et al., 2020). These processes, involving a wide range of plasma regions and phenomena which mutually interact with both the magnetosphere and ionosphere, are usually non linear.…”