Exploring Two‐Dimensional and Three‐Dimensional Propagation of Large‐Scale Traveling Ionospheric Disturbances During the May 2024 Geomagnetic Storm Main Phase
Ting Zhang, Yunbin Yuan, Xingliang Huo, Min Li, Kaixin Wang
Abstract
Abstract During the main phase of the May 2024 super geomagnetic storm, we investigated large‐scale traveling ionospheric disturbances (LSTID) using data from densely distributed global GNSS receivers. From both two‐dimensional and three‐dimensional (3D) perspectives, we analyzed LSTID propagation characteristics over North America, European, and Australia. Global detrended total electron content (dTEC) time‐sequence maps revealed multiple alternating positive and negative TEC perturbation bands propagating from high to low latitudes, with wavelengths exceeding 1,000 km—typical signatures of LSTID. The strongest disturbances occurred over North America, approaching ±4.0 TECU at 19:00 UT. Estimated meridional propagation speeds ranged from 550 to 570 m/s (19:40 UT) in the North America, 720–730 m/s (18:30 UT) in the European, and 530–540 m/s (18:40 UT) and 730–770 m/s (23:20 UT) in the Australian sector, aligning with known mid‐ and high‐latitude LSTID characteristics. Using GNSS‐based 3D ionospheric tomography, we identified the vertical propagation of LSTID, which was confirmed by ionosonde and SwarmA, demonstrating the method's ability to capture hmF2 dynamics. Furthermore, the AMPERE field‐aligned currents (FACs) and the associated Joule heating exhibit strong spatiotemporal correlation with the observed LSTID, suggesting that high‐latitude FAC‐driven energy input, particularly in the form of Joule heating, plays a critical role in their generation and equatorward propagation. Our study highlights the importance of capturing the three‐dimensional characteristics of LSTID during the storm's main phase to better understand high‐to‐low latitude energy coupling in the ionosphere.