Abstract
We report new findings of total electron content (TEC) perturbations in
the southern hemisphere at conjugate locations to the northern eclipse
on 21 August 2017. We identified a persistent conjugate TEC depletion by
10-15\% during eclipse time, elongating along magnetic
latitudes with $\sim$5$^\circ$
latitudinal width, moving equatorward, and becoming most pronounced at
lower magnetic latitudes
($<$20$^\circ$S) when the ionosphere in
the northern low latitudes were masked. This depletion was coincident
with a weakening of the southern crest of the equatorial ionization
anomaly (EIA), while the northern EIA crest stayed almost undisturbed or
was slightly enhanced. We suggest these conjugate perturbations were
associated with dramatic eclipse initiated plasma pressure reductions in
the flux tubes, with a large portion of shorter tubes located at low
latitudes underneath the Moon’s shadow. These small L-shell tubes
transversed the F region ionosphere at low and equatorial latitudes. The
plasma pressure gradient was markedly skewed northward in the flux tubes
at low and equatorial latitudes, as was the neutral pressure. These
effects caused a general northward motion tendency for plasma within the
flux tubes, and inhibited normal southward diffusion of equatorial
fountain plasma into the southern EIA region.