10:00 〜 10:15
[PEM12-05] Observations of Ionospheric Disturbances driven by eruption of Hunga-Tonga-Hunga-Ha'apai volcano using FORMOSAT-7/COSMIC-2
キーワード：FORMOSAT-7/COSMIC-2 , global ionospheric specification, traveling ionospheric disturbances
The global low-latitude ionosphere observations given by the Tri-GNSS radio occultation system (TGRS) and ion velocity meter (IVM) onboard the FORMOSAT-7/COSMIC-2 (F7/C2) have been applied to study the ionosheric responses to the moderate geomagnetic storms. Results show that the ionosphere responses are much greater than expectation as the moderate storms could double or triple the electron density, which was only possible during major magnetic storms under higher solar activity conditions. On January 15th 2022, the Tonga volcano eruption unleashed a strong global atmosphere perturbations and coincided with a moderate geomagnetic storm. The ensuing thermospheric variations created a rare display of extreme poleward-expanding conjugate plasma bubbles in rate of total electron content indices over 100-150°E, also causing ion-density fluctuations in IVM measurements reaching ~40°N geographic latitude. This was preceded by an unusually strong pre-reversal enhancement (PRE) of low latitude ionosphere as seen from the global ionospheric specification (GIS) which is constructed based on the TGRS observations. The GIS further revealed sharp decrease of equatorial ionization anomaly (EIA) crest density due to the storm impact. The enhanced F-region wind over EIA by the negative storm, when combined with volcano induced E-region westward disturbance wind, apparently intensified the PRE. In presence of the strong PRE, seed perturbations from volcano induced variations triggered the super plasma bubble activity.