2015年3月磁暴期间海南地区等离子体泡观测分析

    Observation and Analysis of Plasma Bubbles in Hainan during the Magnetic Storm in March 2015

    • 利用子午工程富克站(19.5°N, 109.1°E) 630 nm气辉成像仪、电离层测高仪、VHF雷达回波强度数据和Dalat地磁台站(11.9°N, 108.5°E; GL:2.5°)、PHU Thuy地磁台站(21.0°N, 105.9°E; GL:11.5°)地磁水平分量数据及ACE卫星的行星际磁场、太阳风速度观测数据, 针对2015年3月特大磁暴期间海南上空电离层等离子体泡进行了研究. 结果显示, 磁暴前后均观测到午夜前等离子体泡和日落后电离层底部虚高的抬升现象; 磁暴期间电离层底部虚高抬升受到明显抑制, 富克站未观测到等离子体泡. 对行星际电/磁场及地磁水平分量的变化情况的分析表明, 磁暴期间电离层翻转前增强(Pre-Reversal Enhancement, PRE)电场可能先后被西极性过屏蔽穿透电场和扰动发电机电场抑制, 导致瑞利–泰勒不稳定性降低, 不利于等离子体泡/电离层不规则体结构的发育.

       

      Abstract: This study utilizes the optical observation data from the 630 nm all-sky airglow imager, the data from the ionospheric digital ionosonde, and the data of the echo intensity of the Very High Frequency (VHF) coherent scatter radar at the Fuke Station in Hainan of the Meridian Project (19.5°N, 109.1°E). In combination with the geomagnetic horizontal component data from the Dalat Geomagnetic Station (11.9°N, 108.5°E; GL:2.5°) and the PHU Thuy Geomagnetic Station (21.0°N, 105.9°E; GL:11.5°), as well as the observations of the interplanetary magnetic field and solar wind speed from the ACE satellite, the study is carried out on the variations of the ionospheric plasma bubbles/irregularity structures over Hainan during the super geomagnetic storm in March 2015. The results show that the appearance of pre-midnight plasma bubbles and the uplift of the virtual height at the bottom of the ionosphere after sunset were observed both before and after the geomagnetic storm. However, the plasma bubbles observed after the end of the geomagnetic storm were of a fossil structure, which may be due to the fact that the ionospheric electric field during the occurrence period of the plasma bubbles on that day showed a westward polarity, which was not conducive to the development of the plasma bubbles. The uplift of the virtual height at the bottom of the ionosphere during the geomagnetic storm was significantly suppressed, and no plasma bubbles were observed at the Fuke station. The analysis of the variations of the interplanetary electric/magnetic field and the geomagnetic horizontal component shows that the Pre-Reversal Enhancement (PRE) electric field before the ionospheric reversal during the geomagnetic storm may have been successively suppressed by the over-shielding penetrating electric field with a westward polarity and the Disturbance Dynamo Electric Field (DDEF), resulting in a decrease in the Rayleigh-Taylor instability, which is not conducive to the development of the plasma bubble/ionospheric irregularity structures.

       

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