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Low‐cost instrumentation combined with volunteering and citizen science educational initiatives allowed the deployment of L‐band scintillation monitors to remote sense areas that are geomagnetically conjugated and located at low‐to‐mid latitudes in the American sector (Quebradillas in Puerto Rico and Santa Maria in Brazil). On 10 and 11 October, 2023, both monitors detected severe scintillations, some reaching dip latitudes beyond 26°N. The observations show conjugacy in the spatio‐temporal evolution of the scintillation‐causing irregularities. With the aid of collocated all‐sky airglow imager observations, it was shown that the observed scintillation event was caused by extreme equatorial plasma bubbles (EPBs) reaching geomagnetic apex altitudes exceeding 2,200 km. The observations suggest that geomagnetic conjugate large‐scale structures produced conditions for the development of intermediate scale (few 100 s of meters) in both hemispheres, leading to scintillation at conjugate locations. Finally, unlike previous reports, it is shown that the extreme EPBs‐driven scintillation reported here developed under geomagnetically quiet conditions. Plain Language Summary: The ionosphere is a region of the Earth's upper atmosphere characterized by a relatively large density of free ions and electrons produced, mainly, by solar photoionization. Ionospheric equatorial plasma bubbles (EPBs) are drastic decreases in ionospheric density known to develop near the equator during nighttime and expand to low latitudes. EPBs cause fluctuations in transionospheric signals transmitted by global navigation satellite systems (GNSS) such as the GPS (global positioning system). In this report, we present the results of a study made possible by low‐cost, GNSS‐based sensors hosted by volunteers and citizen science educational initiatives. The study evaluated the behavior of scintillation in the northern and southern hemispheres at low‐to‐mid latitudes. We found similar spatio‐temporal behavior in the scintillation events observed by monitors deployed in geomagnetically conjugate areas in the northern and southern hemispheres. We also found that the observed scintillation events were associated with EPBs that reached low‐to‐mid latitudes (extreme EPBs). Although these events are more likely to occur under disturbed geophysical conditions, the case presented here took place during a quiet period. The results indicate that GNSS systems at low‐to‐mid latitudes can be affected by EPBs‐driven scintillation more often than previously anticipated. Key Points: Citizen science initiatives allowed simultaneous observations of scintillation over geomagnetic conjugate areas at low‐to‐mid latitudesThe observations show a conjugacy in the spatio‐temporal evolution of intermediate scale size ionospheric irregularitiesLow‐to‐mid latitude scintillations were associated with extreme EPBs (reaching dip latitudes >26°) during quiet conditions [ABSTRACT FROM AUTHOR]

Abstract The occurrence of plasma irregularities and ionospheric scintillation over the Caribbean region have been reported in previous studies, but a better understanding of the source and conditions leading to these events is still needed. In December 2021, three ground-based ionospheric scintillation and Total Electron Content monitors were installed at different locations over Puerto Rico to better understand the occurrence of ionospheric irregularities in the region and to quantify their impact on transionospheric signals. Here, the findings for an event that occurred on March 13–14, 2022 are reported. The measurements made by the ground-based instrumentation indicated that ionospheric irregularities and scintillation originated at low latitudes and propagated, subsequently, to mid-latitudes. Imaging of the ionospheric F-region over a wide range of latitudes provided by the GOLD mission confirmed, unequivocally, that the observed irregularities and the scintillation were indeed caused by extreme equatorial plasma bubbles, that is, bubbles that reach abnormally high apex heights. The joint ground- and space-based observations show that plasma bubbles reached apex heights exceeding 2600 km and magnetic dip latitudes beyond 28°. In addition to the identification of extreme plasma bubbles as the source of the ionospheric perturbations over low-to-mid latitudes, GOLD observations also provided experimental evidence of the background ionospheric conditions leading to the abnormally high rise of the plasma bubbles and to severe L-band scintillation. These conditions are in good agreement with the theoretical hypothesis previously proposed. Graphical Abstract

The occurrence of plasma irregularities and ionospheric scintillation over the Caribbean region have been reported in previous studies, but a better understanding of the source and conditions leading to these events is still needed. In December 2021, three ground-based ionospheric scintillation and Total Electron Content monitors were installed at different locations over Puerto Rico to better understand the occurrence of ionospheric irregularities in the region and to quantify their impact on transionospheric signals. Here, the findings for an event that occurred on March 13–14, 2022 are reported. The measurements made by the ground-based instrumentation indicated that ionospheric irregularities and scintillation originated at low latitudes and propagated, subsequently, to mid-latitudes. Imaging of the ionospheric F-region over a wide range of latitudes provided by the GOLD mission confirmed, unequivocally, that the observed irregularities and the scintillation were indeed caused by extreme equatorial plasma bubbles, that is, bubbles that reach abnormally high apex heights. The joint ground- and space-based observations show that plasma bubbles reached apex heights exceeding 2600 km and magnetic dip latitudes beyond 28°. In addition to the identification of extreme plasma bubbles as the source of the ionospheric perturbations over low-to-mid latitudes, GOLD observations also provided experimental evidence of the background ionospheric conditions leading to the abnormally high rise of the plasma bubbles and to severe L-band scintillation. These conditions are in good agreement with the theoretical hypothesis previously proposed. [ABSTRACT FROM AUTHOR]