15:00 〜 15:15
[PEM15-16] The Characteristics and Possible Mechanisms of the Ionospheric Irregularities during the Geomagnetic storm on 3 March 2024
キーワード：ionospheric irregularities, equatorial plasma bubbles, geomagnetic storm
A geomagnetic storm occurred on 3 March 2024, with the minimum SYM-H reaching −127 nT. Although this geomagnetic storm was not very strong, the ionospheric irregularities on this day resulted in a strong ionospheric scintillation. The amplitude scintillation index was larger than 1.0. Global Navigation Satellite System (GNSS) receivers experienced numerous cycle slips and loss of lock of carrier phase over a large longitudinal range of ~30 degrees within ~5 hours in the south of China. Ground-based GNSS receivers, ionosondes and in situ satellite measurements were utilized to analyze the characteristics of the equatorial plasma bubbles (EPBs) during this event. Post-sunset EPBs and morning EPBs were detected by multi instruments. The post-sunset EPBs began before the main phase of the geomagnetic storm and extended to 30 oN in latitude. The EPBs drifted eastward during their evolution. Three uplifts of the ionosphere were observed during the existence of the post sunset EPBs. It is suggested that the three uplifts were respectively related to the pre-reversal enhancement (PRE) of the eastward electric field, the storm-time prompt penetration electric filed (PPEF) and equatorward neutral wind. PRE might play a vital role in the initial generation of the post-sunset EPBs. PPEF and equatorward neutral wind were conductive to the development of the EPBs. As for the morning EPBs, the observations showed they were freshly generated at ~05:00LT, not the persistence of the post sunset EPBs. The morning EPBs drifted westward and survived for ~4 hours. Unlike the post sunset EPBs, they did not cause loss of lock or cycle slip. Accompanying the generation of the morning EPBs, the height of the ionosphere was uplifted once again. The uplift was more obvious at low latitudes. Disturbance dynamo electric fields might contribute to the uplift of the ionosphere and the generation of the morning EPBs. Moreover, large-scale wave structures (LSWS) could potentially serve as the seeding source of the post-sunset and morning EPBs during this event.