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.