Intense and Regional Counter Electrojet Reveals Wind‐Driven Mechanism of Equatorial Current

This is the authors' abstract. We don't add key points for this paper.

The equatorial electrojet (EEJ) is an ionospheric current that typically flows eastward along the geomagnetic equator, but occasionally reverses to the westward direction, forming what is known as the counter electrojet (CEJ). The mechanism driving CEJ remains highly controversial. This study investigated the reversal mechanism by analyzing the equatorial currents during the Mother's Day weekend geomagnetic storm, the largest geomagnetic storm in 25th solar cycle. We combined the space‐borne geomagnetic data from Swarm and CSES (China Seismo‐Electromagnetic Satellite), ground‐based geomagnetic data from INTERMAGNET and IGP, along with the thermospheric wind observations from FPIs and meteor radars for analysis. Our results reveal that the CEJ exhibited a significant difference between noon and afternoon. The wind observations suggest that the presence of strong westward winds above the conventional dynamo regions. Accordingly, we propose a wind‐driven mechanism to explain the local time dependence in CEJ. The uplift of the ionospheric dynamo is beneficial to the wind‐driven mechanism.