Study of ionospheric disturbances by coupling of global and local ionospheric numerical models

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04037
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Kyoto University
• Principal Investigator: Yokoyama Tatsuhiro 京都大学, 生存圏研究所, 准教授 (30397525)
• Co-Investigator(Kenkyū-buntansha): 品川 裕之 九州大学, 国際宇宙惑星環境研究センター, 博士研究員 (00262915) ; 陣 英克 国立研究開発法人情報通信研究機構, 電磁波研究所宇宙環境研究室, 主任研究員 (60466240)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 電離圏 / プラズマバブル / シミュレーション

Outline of Final Research Achievements

Equatorial plasma bubbles (EPBs) are a well-known phenomenon in the equatorial ionosphere that causes severe scintillation in the amplitude and phase of radio signals. To forecast the occurrence of EPBs, a new simulation model has been developed to simulate the EPB generation and global plasma drift velocity in the whole longitude with a multi-scale grid system. 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 background 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.

Free Research Field

電離圏物理学

Academic Significance and Societal Importance of the Research Achievements

プラズマバブルは電波伝搬に影響を及ぼし、短波通信やGNSS即位に深刻な障害をもたらすため、プラズマバブルの発生を予測することは安定かつ正確な通信・即位を実現する上で非常に重要な課題である。本研究によって、数値モデルのみによるプラズマバブルの発生予測が非常に困難であるという点が改めて認識された点と、様々な観点から観測とシミュレーションを実施する必要がある点を示した点に意義があると言える。