Simultaneous occurrence of three non-interacting characteristically
different ionospheric plasma structures over the geomagnetic low-mid
latitude transition region
Abstract
An unusual event of three characteristically different plasma structures
on a geomagnetically quiet night (Ap = 4) of 08 July 2018 has been
investigated in this paper using an all-sky imager installed at Hanle,
Leh Ladakh (32.7°N, 78.9°E; Mlat. ~24.1°N), India. These
structures include a freshly generated electrified MSTID (EMSTID),
ambiguous plasma depletions, and a northward propagating non-electrified
MSTID. One of the most fascinating aspects of this event was the lack of
mutual interaction between the three structures, even though they
existed simultaneously and propagated in different directions. They
individually underwent evolution, distortion, and dissipation
separately. One of the structures was an EMSTID, which got generated
within the imager’s field-of-view (FOV) and evolved with time. As time
progressed, different strip-like structures travelled southwestward,
merged with each other to form the EMSTID and disappeared later. The
second structure was plasma depletions which appeared in the
southeastern part of the FOV. They eventually merged into a single band.
The merged band evolved with time, extended further northward, and
dissipated later. Along with these, a very rare non-electrified MSTID
structure with east-west aligned fronts was observed which propagated
northward. Its fronts underwent distortion, became curved and
dissipated. In this study, we have explored the role of electrodynamics
and neutral dynamics behind the observed unique features of the three
plasma structures.