17:15 〜 18:45
[PEM12-P17] SuperDARNレーダーによる夜間MSTID発生に関する季節依存性・太陽活動度依存性の統計解析研究
キーワード：SuperDARN、中規模伝搬性電離圏擾乱
Medium-scale traveling ionospheric disturbances (MSTIDs) are propagating wave-like electron density disturbances in the ionosphere and can be observed in Super Dual Auroral Radar Network (SuperDARN) data. Previous studies have shown that nighttime MSTIDs north of Hokkaido propagate mainly southwestward, and their propagation characteristics depend on season and solar activity. Southwestward propagation of nighttime MSTIDs is particularly dominant in winter, and the nighttime MSTIDs amplitude has a negative correlation with solar activity.
In this study, we conduct a statistical analysis on nighttime MSTIDs using the SuperDARN Hokkaido East (43.53 N, 143.61 E), Hokkaido West (43.54 N, 143.61 E), Christmas Valley East (43.27 N, 120.36 W), and Christmas Valley West (43.27 N, 120.36 W) High-Frequency (HF) radar data from 2020 to 2023. This analysis period contains the solar activity increasing period that was not included in the analysis period of the previous study made by Hazeyama et al. (2022, JGR) or Hazeyama et al. (2022, Master Thesis). The current study aims to analyze the nighttime MSTIDs in the new solar activity cycle. We utilized the line-of-sight Doppler velocity data, which correspond to the magnitude of the polarization electric field associated with nighttime MSTIDs. We find that the propagation direction of the nighttime MSTIDs is mainly southwestward. On the other hand, the correlation between the nighttime MSTIDs amplitude and the solar F10.7 index is different between Hokkaido (negative correlation) and Christmas Valley (positive correlation) radars. These tendencies can be interpreted in terms of the Perkins instability associated with nighttime MSTIDs' growth, which is affected by the electric field intensity depending on the magnetic latitude during disturbed geomagnetic activity.
In this study, we conduct a statistical analysis on nighttime MSTIDs using the SuperDARN Hokkaido East (43.53 N, 143.61 E), Hokkaido West (43.54 N, 143.61 E), Christmas Valley East (43.27 N, 120.36 W), and Christmas Valley West (43.27 N, 120.36 W) High-Frequency (HF) radar data from 2020 to 2023. This analysis period contains the solar activity increasing period that was not included in the analysis period of the previous study made by Hazeyama et al. (2022, JGR) or Hazeyama et al. (2022, Master Thesis). The current study aims to analyze the nighttime MSTIDs in the new solar activity cycle. We utilized the line-of-sight Doppler velocity data, which correspond to the magnitude of the polarization electric field associated with nighttime MSTIDs. We find that the propagation direction of the nighttime MSTIDs is mainly southwestward. On the other hand, the correlation between the nighttime MSTIDs amplitude and the solar F10.7 index is different between Hokkaido (negative correlation) and Christmas Valley (positive correlation) radars. These tendencies can be interpreted in terms of the Perkins instability associated with nighttime MSTIDs' growth, which is affected by the electric field intensity depending on the magnetic latitude during disturbed geomagnetic activity.