We employ multi-instrumental data to investigate the behavior of equatorial and low latitude ionosphere during the geomagnetic storm of November 3-6, 2021. We used TEC data obtained from GPS receiver stations located in the equatorial and low-latitudes of the Asian, African, and American sectors. It is found that the storm-time ionization level varies significantly in the trough and crest of EIA region over the three longitudes. ROTI is used to estimate the occurrence of ionospheric plasma irregularities during the storm. Usually, the main phase of the geomagnetic storm triggers the equatorial plasma irregularities and the recovery phase suppresses the occurrence of them. Here, we observed inhibition of the plasma irregularities over the three sectors during the main phase of the storm. We suspect this may be due to the injection of the PEFs which occur between local midnight and around noon during the main phase. The PEFs restrict the diffusion of plasma and therefore, suppress the occurrence of plasma irregularities during the main phase. During the recovery phase, moderate ionospheric irregularities occurred at local midnight in the American sector. In the African sector, the occurrence of weak irregularities can be seen before midnight on November 5 and 6. However, the Asian sector does not exhibit noticeable ionospheric irregularities during the storm. We conclude that the longitudinal variation in the development of ionospheric irregularities can be influenced by factors such as local time occurrence of maximum ring current, PPEF, disturbance wind dynamo electric field, and shielding electric field.

The lunar ionosphere is a ~100 km thick layer of electrically charged plasma surrounding the moon. Despite knowledge of its existence for decades, the structure and dynamics of the lunar plasma remain a mystery due to lack of consistent observational capacity. An enhanced observational picture of the lunar ionosphere and improved understanding of its formation/loss mechanisms is critical for understanding the lunar environment as a whole and assessing potential safety and economic hazards associated with lunar exploration and habitation. To address the high priority need for observations of the electrically charged constituents near the lunar surface, we introduce a concept study for the Radio Instrument Package for Lunar Ionospheric Observation (RIPLIO). RIPLIO would consist of a multi-CubeSat constellation (at least two satellites) in lunar orbit for the purpose of conducting “crosslink” radio occultation measurements of the lunar ionosphere, with at least one satellite carrying a very high frequency (VHF) transmitter broadcasting at multiple frequencies, and at least one satellite flying a broadband receiver to monitor transmitting satellites. Radio occultations intermittently occur when satellite-to-satellite signals cross through the lunar ionosphere, and the resulting phase perturbations of VHF signals may be analyzed to infer the ionosphere electron content and high- resolution vertical electron density profiles. As demonstrated in this study, RIPLIO would provide a novel means for lunar observation, with the potential to provide long-term, high-resolution observations of the lunar ionosphere with unprecedented pan-lunar detail.