17:15 〜 19:15
[PEM14-P14] 数値シミュレーションによるトンガ沖海底火山噴火に伴う電離圏擾乱の研究
キーワード：電離圏、シミュレーション、噴火、MSTID
When the eruption of Hunga Tonga-Hunga Ha'apai occurred on 15 January 2022, medium-scale traveling ionospheric disturbances (MSTIDs) appeared not only around the epicenter but also in the magnetic conjugate region. Although the mechanism of this phenomenon has been speculated, simulations performed before have not been able to reproduce this phenomenon. The purpose of this study is to clarify the mechanism of MSTIDs generation at the magnetic conjugate point by simulation using the midlatitude ionosphere electrodynamics coupling (MIECO) model which has been used to study the generation of MSTIDs via E-F region coupling.
Neutral wind perturbation driven by the eruption has been simulated by nonhydrostatic atmosphere model (NHM). As a first try, we approximate the vertical wind perturbation by a simple mathematical function and use it as an input parameter for the MIECO model. The maximum amplitude is assumed to be 300 m/s as expected from the NHM results and the horizontal wind perturbation is ignored. In the Southern Hemisphere, the plasma density is modulated by both the vertical wind and polarization electric field, while the plasma density in the Northern Hemisphere is modulated only by the polarization electric field generated in the Southern Hemisphere. This perturbation could be a seeding of MSTIDs under a favorable condition for the growth of the Perkins instability in the midlatitude ionosphere. By incorporating the neutral wind data from NHM, we will try to simulate the generation of MSTIDs driven by electrodynamical coupling effects before the arrival of atmospheric waves excited by the eruption.
Neutral wind perturbation driven by the eruption has been simulated by nonhydrostatic atmosphere model (NHM). As a first try, we approximate the vertical wind perturbation by a simple mathematical function and use it as an input parameter for the MIECO model. The maximum amplitude is assumed to be 300 m/s as expected from the NHM results and the horizontal wind perturbation is ignored. In the Southern Hemisphere, the plasma density is modulated by both the vertical wind and polarization electric field, while the plasma density in the Northern Hemisphere is modulated only by the polarization electric field generated in the Southern Hemisphere. This perturbation could be a seeding of MSTIDs under a favorable condition for the growth of the Perkins instability in the midlatitude ionosphere. By incorporating the neutral wind data from NHM, we will try to simulate the generation of MSTIDs driven by electrodynamical coupling effects before the arrival of atmospheric waves excited by the eruption.