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Abstract We report an extraordinary L‐band scintillation event detected in the American sector on the night of 23–24 March 2023. The event was detected using observations distributed from the magnetic equator to mid latitudes. The observations were made by ionospheric scintillation and total electron content (TEC) monitors deployed at the Jicamarca Radio Observatory (JRO, ∼−1° dip latitude), at the Costa Rica Institute of Technology (CRT, ∼20° dip latitude), and at The University of Texas at Dallas (UTD, ∼42° dip latitude). The observations show intense pre‐ and post‐midnight scintillations at JRO, a magnetic equatorial site where L‐band scintillation is typically weak and limited to pre‐midnight hours. The observations also show long‐lasting extremely intense L‐band scintillations detected by the CRT monitor. Additionally, the rare occurrence of intense mid‐latitude scintillation was detected by the UTD monitor around local midnight. Understanding of the ionospheric conditions leading to scintillation was assisted by TEC and rate of change of TEC index (ROTI) maps. The maps showed that the observed scintillation event was caused by equatorial plasma bubble (EPB)‐like ionospheric depletions reaching mid latitudes. TEC maps also showed the occurrence of an enhanced equatorial ionization anomaly throughout the night indicating the action of disturbance electric fields and creating conditions that favor the occurrence of severe scintillation. Additionally, the ROTI maps confirm the occurrence of pre‐ and post‐midnight EPBs that can explain the long duration of low latitude scintillation. The observations describe the spatio‐temporal variation and quantify the severity of the scintillation impact of EPB‐like disturbances reaching mid latitudes. 

Abstract In this work, it is demonstrated that substorm‐driven penetration electric fields can efficiently enhance the upward plasma transport, favoring the development and structuring of plasma irregularities and the occurrence of scintillation on L‐band signals. While most previous studies focus on investigating penetration electric fields during intense geomagnetic storms, here, the period used (April 01–05, 2020) was under very mild geomagnetic activity (−27 nT SYM‐H 6 nT), so that interplanetary and disturbance dynamo contributions are minimized. This period comprised the same seasonal and solar flux conditions, while undergoing multiple short‐lived substorms, making it well‐suited to evaluate unequivocally: (a) to what extent substorm‐driven penetration electric fields alter electrodynamical processes over low latitudes, and (b) how effective they are in contributing to the structuring of the early nighttime ionosphere and the subsequent occurrence of severe scintillation on L‐band signals. Ground‐based and space‐based multi‐instrument data sets were used. The results show that, even under weak geomagnetic activity, substorm‐driven penetration electric fields—despite being subtle and short‐lived—play a decisive role, enhancing the upward drifts, favoring the development of equatorial plasma bubbles and severe scintillation. The findings indicate that substorms with onsets coinciding with early nighttime are more impactful. This decisive contribution is more likely to be identified during late spring and early fall in the northern hemisphere (or vice versa in the southern hemisphere), when the prereversal vertical drifts are moderate—neither too small nor too large—and may have direct impacts on the day‐to‐day variability of equatorial plasma bubbles.