In-situ Observations of Ionospheric Plasma Blobs Over Nigeria (9.08⁰N, 8.67⁰E) During Deep Solar Minimum: Possible Influence of Small-Scale Fluctuations in Ionospheric Plasma Density

Abstract

Ionospheric plasma blobs have long been studied since it was first reported in 1986. Blobs are localized regions of enhanced plasma with a factor of 2 or 3 above ambient plasma. In this paper, we studied the occurrence of blobs over Nigeria (9.08⁰N, 8.67⁰E geographic coordinates) using the SWARM constellation satellites – ionospheric plasma density dataset specifically. We considered only the nighttime pass of the satellites over Nigeria with time frame 18:00 to 04:59 LT. The satellites passed over Nigeria 126 times in 2019 with 41 cases of plasma blobs. The results show that 58% of the cases were found without bubbles nearby, 29% of the cases were found in the presence of small-scale fluctuations in ionospheric plasma density (henceforth “SSFiI”). From the spectral analysis, the average wavelength, period and the propagating speed of SSFiI are 11 km, 2-4 seconds, and 2.75 – 5.5 km/s, respectively. The rate of change of the electron density inside the blobs associated with SSFiI was ~50% above that of the blobs in the absence of SSFiI. This suggests that bubbles may not be the only prerequisite for the development and dynamics of blobs; and SSFiI may play a significant role in the morphology and dynamics of blobs.