Equatorial to Low-latitude Ionosphere-Thermosphere Dynamics during Geomagnetic Disturbances

In the equatorial and low latitude ionosphere, the equatorial ionization anomaly (EIA) is the most striking large-scale phenomenon. Embedded within EIA are low-density smaller-scale structures, i.e., the equatorial plasma bubbles (EPBs), which occur preferentially over the post-sunset local times. EPBs are known to host ionospheric irregularities that can cause severe satellite signal scintillation and even signal loss of lock, thereby affecting communication and navigation.

The overarching science goal of this project to deepen our understanding of various factors affecting the EIA and EPB growth during geomagnetic disturbances using a comprehensive observational instrument suite and state-of-the-art numerical models [Jin et al., 2018, Aa et al., 2018a, 2018b, 2019, 2020, Jin et al., 2021].

Example of EIA and EPBs from GPS TEC and GOLD. In situ density observations from SWARM are shown on the right. (From Aa, E., Zou, S., et al. 2019, “Coordinated ground-based and space-based observations of equatorial plasma bubbles”)

Super EPBs have been observed to extend to mid latitude region, i.e., ~40 degree mlat, which map to ~4000 km altitude [Aa et al., 2018, 2019, 2024]. Recently, using coupled GITM-SAMI3, we demonstrated that the storm-time penetration electric field plays an essential role in the formation of the super EPBs [Wang et al., 2024].

Simulated post-sunset super EPB formation during the Sep. 7, 2017 storm (left). No post-sunset super EPB formation if no penetration electric field used (middle). The larger the penetration electric field, the stronger the post-sunset super EPB (right). Adapted from Wang et al., 2024.