[P-EM15] 太陽地球系結合過程の研究基盤形成

[PEM15-P04] Simulation of Day-to-day Variability of Equatorial Plasma Bubbles Under Various Background Conditions

*横山 竜宏¹、湯谷 樹生¹ (1.京都大学生存圏研究所)

キーワード：赤道プラズマバブル、シミュレーション、HIRBモデル

Equatorial plasma bubbles (EPBs) are a well-known phenomenon in the equatorial ionospheric F region. As it causes severe scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPB from a space weather point of view. In order to simulate the instability in the equatorial ionosphere, a 3D High-Resolution Bubble (HIRB) model has been developed. It provides a unique opportunity to characterize intermediate-scale EPB structure, which was not well resolved until very recently. In order to study the day-to-day variability of EPB occurrence, we have conducted a number of simulation runs under various conditions by changing backgroudn electric field and electron density. Suitable and unsuitable conditions for the generation of EPBs have been investigated by comparing with the linear growth rate of Rayleigh--Taylor instability. We have found that even a small difference of the linear growth rate could result in a significant difference of the EPB growth, which leads to the difficulty of the prediction of the day-to-day variability of EPB occurrence.