ST2.6

How to cite: Horaites, K., Alho, M., Battarbee, M., Dubart, M., Ganse, U., George, H., Grandin, M., Manglayev, T., Palmroth, M., Papadakis, K., Suni, J., Tarvus, V., Turc, L., Zaitsev, I., and Zhou, H.: Three-dimensional Hybrid-Vlasov Simulations of Geomagnetic Storms, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4687, https://doi.org/10.5194/egusphere-egu22-4687, 2022.

Auroral Kilometric Radiation (AKR) is terrestrial radio emission that originates from high latitude magnetic field lines. The intensity of AKR increases when the magnetosphere is perturbed, and so can indicate the presence of driving from the solar wind. This is true for structures that can vary in scale such as pressure pulses, as well as substorm onsets that follow periods of negative turnings in the Z component of the interplanetary magnetic field. In the latter case, AKR intensification correlates with the strengthening of high-latitude current systems in the ionosphere as the magnetotail current is reconfigured. As well as this, morphological changes in the AKR source region have also been observed to coincide with substorm onset, with an intensification of the AKR emission often accompanied by a low frequency extension, interpreted as an expansion of the source region to higher altitudes along the field line. Although the directivity and source region localisation of AKR make the observations highly dependent on observer local time and latitude, we isolate AKR from Wind radio observations made over a decade and examine the observations with respect to the spacecraft viewing position, accounting for such effects. Using lists of substorm onsets, we examine the AKR power and the spectral extent of the emission with respect to the substorm timeline, expanding on previous studies of the AKR response. Results show a clear increase in AKR power that precedes substorm onset by approximately 20 minutes, and confirm a proportionally higher intensification in lower frequency AKR sources. This in turn indicates quantitatively the spatial response of parallel electric fields after the loading of magnetic flux during substorm growth phase. In characterising the typical AKR response during substorms, these results can inform observations of magnetospheric changes during sudden commencement events and those that are seperate from substorm dynamics.

How to cite: Waters, J., Jackman, C., Whiter, D., Forsyth, C., Fogg, A., Lamy, L., Cecconi, B., Bonnin, X., and Issautier, K.: A perspective on substorm dynamics from 10 years of Auroral Kilometric Radiation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8149, https://doi.org/10.5194/egusphere-egu22-8149, 2022.

Solar wind pressure pulses are known to modify electrodynamics of the terrestrial magnetosphere. In this paper, we present a possible electrodynamic reaction of the ionosphere to a small and brief pressure pulse observed by local and non-local instrument systems over Arecibo Observatory, Puerto Rico and extending over at least the mesoscale. Initially, a strong, four hour long, mid-latitude spread-F-like event was observed through a high frequency, wide-beam radar system, Penn State Ionospheric Radar Imager (PIRI), deployed near Arecibo (18.36◦ E, 66.75◦ S, and f = 4.42 MHz). The same spread-F event was also observed using the dual, narrow-beam 430 MHz Arecibo incoherent scatter radar. Furthermore, GPS delta-vTEC measurements from Carribean island sector revealed that the event was apparently moving from west to east and then east to west crossing over Arecibo twice. Similar GPS-TEC measurements from the South American sector showed that an equatorial spread-F was also present. We use SuperMAG magnetometer and NASA’s OMNI solar wind data to show that a small solar wind pressure pulse and rapid changes in the solar wind magnetic field are likely causes for the observed ionospheric features over Arecibo.

How to cite: Bostan, S. M., Urbina, J. V., Mathews, J. D., and Dinsmore, R. L.: A Non-Local Spread-F-like Event Over Arecibo as the Possible Result of a Solar Wind Pressure Pulse, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10089, https://doi.org/10.5194/egusphere-egu22-10089, 2022.

Pc5 waves are a sub-group of ultra-low frequency (ULF) waves in the magnetosphere. We determine the Pc5 wave power from ground magnetometer measurements in IMAGE network and statistically study their dependence on solar wind conditions, like solar wind speed and dynamic pressure, separating them from the solar phase and solar conditions in a statistical sense.

Pc5 power is dependent on the magnetic local time, season, and magnetic latitude. We show that while it is always heavily modulated by solar wind speed, the intensity of its ground response also varies over time. Particularly, the ground response is usually the strongest in the morning and midnight hours, while a minor maximum can sometimes be found in the midday or afternoon hours.

How to cite: Hynönen, R. and Tanskanen, E.: Ground response of seasonal Pc5 power to varying solar wind conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12854, https://doi.org/10.5194/egusphere-egu22-12854, 2022.