Extreme poleward expanding super plasma bubbles triggered by Tonga
volcano eruption during the recovery phase of geomagnetic storm
Abstract
The Tonga volcano eruption of 15 January 2022 unleashed a variety of
atmospheric perturbations, coinciding with the recovery phase of a
geomagnetic storm. The ensuing thermospheric variations created rare
display of extreme poleward-expanding conjugate plasma bubbles seen in
the rate of total electron content index (ROTI) over 100-150°E. This is
associated with fluctuations in FORMOSAT-7/COSMIC-2 (F7/C2) ion-density
measurements and spread-F signatures in ionograms, reaching
~40°N geographic latitude. This was preceded by an
unusually strong pre-reversal enhancement (PRE) in the global
ionospheric specification (GIS) electron density profiles derived from
F7/C2 observations. The GIS further revealed a decrease of equatorial
ionization anomaly (EIA) crest density due to the storm impact. A sharp
decrease of E-region conductivity by volcano-induced waves, combined
with enhanced F-region wind over EIA with less ion-drag apparently
intensified the PRE. The strong PRE and seed perturbations from the
volcano-induced waves likely further triggered super plasma bubble
activity.