Midlatitude Neutral Wind Response during the Mother’s Day Super-Intense Geomagnetic Storm Using Observations from the Chinese Meridian Project

The super-intense geomagnetic storm of May 2024, known as the Mother's Day superstorm, is the largest event of its kind in the past two decades. During this storm, the coupled ionosphere-thermosphere system was significantly impacted, accompanied by strong disturbances. Neutral winds play a crucial role in both electro-dynamic and hydro-dynamic processes in the upper atmosphere. For the first time, we analyze the characteristics of neutral winds in the East Asian sector during this geomagnetic storm, using data observed by Dual-Channel Optical Interferometers (DCOIs) as part of the Chinese Meridian Project (CMP). Total Electron Content (TEC) is derived from measurements taken by 77 Global Navigation Satellite System (GNSS) receivers across China and surrounding regions. By combining data from four high-frequency (HF) radars and all Super Dual Auroral Radar Network (SuperDARN) radars in the northern hemisphere, we can effectively analyze the ionospheric convection pattern and its effects on neutral winds.

The results show that a strong equatorward wind, with a maximum meridional component amplitude of approximately 400 m/s, was observed during the storm main phase. In the East Asian sector, this equatorward wind enhancement was associated with a negative storm on the night of May 10, which was marked by a significant reduction in TEC over China and adjacent areas. Additionally, ionospheric convection extended to 43° MLAT, with eastward ion velocities exceeding 800 m/s near 50° MLAT. This contributed to a strengthening of zonal winds in northern China, resulting in a notable eastward surge of approximately 230 m/s in the dawnside sub-auroral region. Wave-like oscillations in neutral winds, associated with storm-time Traveling Atmospheric Disturbances (TADs), were observed by multiple DCOI stations.