Severe L-band scintillation over low-to-mid latitudes caused by an extreme equatorial plasma bubble: joint observations from ground-based monitors and GOLD

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

Introduction

Depletions in the ionospheric Total Electron Content (TEC) and intense radio scintillation are known to occur often over low latitudes (Basu et al. 1976; 1988; Beach and Kintner 2001). It has been shown that these low-latitude TEC depletions are caused by Equatorial Plasma Bubbles (EPBs), which are large-scale (> 10 s of km) manifestations of the Generalized Rayleigh–Taylor instability (GRTi). The GRTi finds favorable growth conditions in the equatorial F-region near sunset hours (Woodman and La Hoz 1976). Scintillation is the result of the diffraction of transionospheric radio waves caused by smaller scale irregularities (100 s of meters to a few km) generated by secondary instabilities within the EPBs (Haerendel et al. 1992). EPBs are known to occur frequently, particularly during equinoxes and summer solstices (Sobral et al. 2002), in most longitude sectors, and the scintillation associated with EPBs is known to be the most intense in the globe (Jiao and Morton 2015; Juan et al. 2018). It is also known that EPBs are field-aligned ionospheric density depletions and, therefore, as they rise over the magnetic equator, they also extend to increasingly higher magnetic latitudes. As a consequence, an EPB reaching high apex altitudes over the equator may extend to latitudes far from the equatorial region. Current research seeks a better understanding of the occurrence of these extreme EPBs and the underlying ionospheric conditions leading to these events. Here the nomenclature extreme EPBs refers to EPBs reaching apex altitudes $\ge$ 2000 km.

EPB research is also motivated by their impact, through scintillation, on various radio systems used for communication, navigation, and remote sensing (Kelly et al. 2014; Moraes et al. 2018; Fernandez et al. 2020; Portella et al. 2021; Carrano et al. 2021; Salles et al. 2021; Sousasantos et al. 2022). These factors have led to the deployment of various observing platforms and routine ionospheric observations at low latitudes. The mid-latitude ionosphere, however, has been thought to be devoid of significant disturbances and threats to radio systems. That led to a reduced number of instrument deployments and observations at mid-latitudes. Notable exceptions were observations made by the Incoherent Scatter Radar (ISR) of the Arecibo Observatory in Puerto Rico (PR). While the observations made by the Arecibo ISR were limited in number and focused on the quiescent ionosphere, they served to provide evidence of the occurrence of ionospheric disturbances that departed significantly from expectations for the mid-latitude region (Mathews et al. 2001a, 2001b). In some cases, observations made by the Arecibo ISR were combined with simultaneous airglow, TEC, or coherent scatter radar measurements to confirm the occurrence of large-scale ionospheric disturbances and smaller scale irregularities (Martinis and Mendillo 2007; Martinis et al. 2009). In most cases, the ionospheric disturbances detected near Arecibo were attributed to Medium-Scale Traveling Ionospheric Disturbances—MSTIDs (Martinis et al. 2010).

Martinis and Mendillo (2007), however, reported the unusual case of airglow depletions over Arecibo that were attributed to an extreme EPB reaching mid-latitudes (apex heights above 2200 km). While airglow measurements are difficult to make, given the requirements of sky conditions, Martinis and Mendillo (2007) were still able to report airglow measurements made in El Leoncito, Argentina, slightly west of the conjugate point of Arecibo in the southern hemisphere, providing convincing observational evidence to support their hypothesis of an extreme EPB as the source of the ionospheric disturbance observed over Arecibo. The equatorial region, however, was not covered by their experiment.

Previous studies using coherent backscatter radar over the Peruvian equatorial region indicated that extreme EPBs are rare events. Chapagain et al. (2009) used 10 years (1996–2006) of radar measurements to investigate the behavior of the maximum height of EPBs (radar plumes) over the equator (Jicamarca) as a function of solar flux conditions. They found that the maximum height of the plumes does increase with F10.7, but few plumes reached 1600 km apex heights. In their data set, they did not find plumes reaching apex heights greater than 1800 km. Notwithstanding, an increasing number of works reported the occurrence of possible extreme EPBs using data from ion density measurements made by instruments boarded in satellites (Basu et al. 2005, 2007; Huang et al. 2007a); from the Global Navigation Satellite System (GNSS) ground receiver networks (Ma and Maruyama 2006; Cherniak and Zakharenkova 2016, 2022; Katamzi-Joseph et al. 2017; Li et al. 2018; Aa et al. 2018; Zakharenkova and Cherniak 2020, 2021; Sori et al. 2022), and all-sky imagers (Martinis et al. 2015). Recently, Rodrigues et al. (2021) reported the occurrence of mid-latitude scintillation and TEC depletions over Southern US (43.2°N magnetic dip latitude) that could have been associated with an extreme EPB as hypothesized by Martinis et al. (2015) or by a super Medium-Scale Traveling Ionospheric Disturbance (MSTID) as proposed by Kil et al. (2016). Also, during unusual events, such as the Hunga Tonga-Hunga Ha’apai volcano eruption, strong ionospheric irregularities over latitudes far away from the geomagnetic equator have been reported (Aa et al. 2022; Rajesh et al. 2022). These results indicate the need of joint space-and-ground-based observations for unequivocal determination of the sources of irregularities and scintillation over mid-latitudes.

This work presents results related to observations made by a new set of ground-based instruments contributing to a better understanding of the occurrence and impact of ionospheric disturbances observed at mid-latitudes. These observations were complemented with images from the Global-scale Observations of the Limb and Disk (GOLD) mission allowing the determination of the source of the ionospheric disturbances reaching dip latitudes > 28°. More specifically, new observations of TEC depletions and severe amplitude scintillations reaching the latitude of Puerto Rico and above are reported. The spatial and temporal behavior of scintillation provided by the ground-based observations indicates that this event was caused by an extreme EPB. Additionally, simultaneous and collocated GOLD observations confirm, unequivocally, that scintillations were caused by an extreme EPB. Moreover, GOLD provided information about the background F-region conditions under which the extreme EPBs and severe scintillation occurred. The observations are in good agreement with hypotheses about the ionospheric conditions favoring the rise of extreme EPBs put forward by previous studies (Mendillo et al. 2005; Krall et al. 2010).

Instrumentation and observations

As part of an ongoing experimental effort that seeks to better understand the occurrence and severity of ionospheric scintillation at mid-latitudes, ScintPi 3.0 (Gomez Socola and Rodrigues 2022) ionospheric monitors were deployed over Puerto Rico. ScintPi 3.0 may be described as an updated version of the ScintPi monitor presented by Rodrigues and Moraes (2019). Instead of a single-frequency Global Positioning System (GPS)-only receiver, however, ScintPi 3.0 uses a dual-frequency GNSS receiver. Consequently, ScintPi 3.0 measures the severity of ionospheric scintillation (S₄ index) at two frequencies (~ 1.2 and ~ 1.5 GHz) using signals transmitted by GPS, Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS), Galileo, and Beidou. The dual-frequency measurements made by SciniPi 3.0 also allow the estimation of the ionospheric TEC. The S₄ index corresponds to the standard deviation of signal intensity normalized by its average (Briggs and Parkin 1963; Yeh and Liu 1982). ScintPi 3.0 monitors were installed at three different sites in Puerto Rico and started observations in December 2021. The location of the sites and relevant information are provided in Table 1.

Table 1 Location of the ScintPi 3.0 monitors and relevant information

A unique set of space-based observations complement ScintPi 3.0 measurements, providing information that was used to determine the origin of the TEC depletions and scintillations observed over Puerto Rico. These observations were made by the NASA GOLD mission, which has a dual-channel ultraviolet-imaging spectrograph on SES-14, a communication satellite in geostationary orbit at 47.5°W longitude. The instrument makes measurements of the Earth far ultraviolet (FUV) airglow at ~ 134–162 nm. GOLD observations include images of the Earth sunlit and nightside disk, limb scans, and stellar occultations, from 06:10 UT up to 00:40 UT each day (Eastes et al. 2020). The nighttime scans cover about 45° in longitude and have a cadence of 15 min per scan.

In this study, the GOLD nighttime partial disk observations of the OI 135.6 nm emission, which serves as a proxy of ionospheric F-region densities, were employed. These observations have been used to track the behavior of the Equatorial Ionization Anomaly (EIA) and the occurrence of EPBs (Eastes et al. 2019; Aa et al. 2019). The observations made on the night of March 13–14, 2022, are analyzed and discussed in this study. During this night, large TEC depletions and severe scintillation events occurred at the latitudes of Puerto Rico and above.

Results and discussion

In this section, the results are summarized and discussed. First, the spatio-temporal evolution of ionospheric scintillation activity during the night of the event is presented. In the sequence, the severity of the TEC depletions, coincident with the occurrence of the scintillation in the signals, is analyzed. Subsequently, the GOLD observations are discussed, providing unequivocal evidence of the extreme EPB event as the source of the TEC depletions and ionospheric scintillation over dip latitudes > 28°. In addition, a discussion on the conditions leading to this extreme EPB event is also presented.

On the spatio-temporal evolution of L-band scintillation

Figure 1 summarizes the observations made by the three ScintPi 3.0 receivers on March 13–14, 2022. It shows S₄ indices (see colorbar) for GNSS ~ 1.2 GHz signals in their corresponding Ionospheric Pierce Points (IPP) at 350 km altitude for sequential hours. Each panel exhibits the results for a time interval of 1 h during which observations were made. These time intervals are indicated in the respective left-bottom corners. Isolines of magnetic dip latitudes (magenta lines) and apex heights (black dashed lines) are also shown for reference. The dip latitudes and apex heights were computed from the International Geomagnetic Reference Field (IGRF13) model for March 2022. Computations considered the magnetic field lines starting points at the nominal F-region peak height (350 km), where irregularities contributing the most to scintillation are believed to be located.

Fig. 1

S₄ indices for all the 1.2 GHz GNSS signals measured by the three ScintPi 3.0 receivers deployed over Puerto Rico. Each panel exhibits an 1-h frame during which observations were made. The time interval is indicated in the left-bottom corner of each panel. The green X markers indicate the location of the monitors. The solid magenta lines show dip latitudes (°), and the dashed black lines indicate the corresponding equatorial apex heights (in km). The S₄ values are represented by colors according to the colormap on the right and by the size of the dots. Only data from satellites with elevation angles greater than 30° were used

The most striking result shown in Fig. 1 is the occurrence of strong scintillation (S₄ > 0.9 at 1.2 GHz) over Puerto Rico and at higher latitudes. The detection of this level of scintillation is unusual for mid-latitudes and is typically reported for observations made near the EIA peak, at lower latitudes. Figure 1 also serves to track the spatio-temporal evolution of the scintillation in the signals. The scintillation was first observed between 23:00 and 24:00 UT on March 13, 2022 at around 21° dip latitude, corresponding to regions with magnetic field lines reaching around 1400 km apex heights. By 01:00–02:00 UT, scintillation extended to higher latitudes and can be seen at dip latitudes > 28^°, i.e., where magnetic field line apex heights are > 2600 km.

On the severity of scintillation and TEC conditions

Figure 1 already shows that moderate and intense scintillation could be observed in signals recorded by the ScintPi 3.0 monitors. Figure 2 better illustrates the severity of the observed scintillations and shows examples of TEC conditions under which these scintillation events occurred. The upper panels (a–c) show the relative slant TEC inferred from signals transmitted by GPS SVID 11 and measured by the ScintPi 3.0 receivers located at Culebra, Arecibo, and Quebradillas, from left to right, respectively. The middle panels (d–f) exhibit the S₄ indices for 1.2 (red) and 1.5 (black) GHz. The lower panel (g) shows the IPPs (at 350 km) of the signals for the three receiving stations. SVID stands for Space Vehicle Identification.

Fig. 2

TEC depletions and ionospheric scintillation recorded by the three ScintPi 3.0 stations over Puerto Rico. Upper panels (a–c): Steep TEC depletions (“bite-outs”) over Culebra, Arecibo, and Quebradillas. Middle panels (d–f): Strong ionospheric scintillation for the L1 (1.5 GHz) and L2 (1.2 GHz) signals transmitted by GPS SVID11 on March 13–14, 2022. Lower panel (g): IPPs of the signals from the GPS SVID11 for the three stations. Please notice that Arecibo and Quebradillas stations are close to each other and their IPPs overlap

Note that Arecibo and Quebradillas are separated by only about 30 km and that the IPPs and measurements for these stations are very similar. As a result, the IPP tracks for these stations on panel (g) overlap. Culebra, however, is located about 200 km to the east of Arecibo, and the measurements are somewhat different. The measurements in the three sites, nevertheless, confirm that intense scintillation occurred in both frequencies. As expected from previous theoretical and experimental studies (Fremouw et al. 1978; Salles et al. 2021), scintillation on 1.2 GHz is stronger than scintillation on 1.5 GHz signals. This example shows S₄ at 1.2 GHz > 0.8. More importantly, the observations serve to illustrate the finding that scintillations were accompanied by steep TEC variations that resemble those observed at lower latitudes during EPB events.

On simultaneous and collocated GOLD observations

The spatio-temporal behavior of the event detected on March 13–14, 2022, indicates that irregularities causing scintillation had origin at low latitudes. More specifically, the scintillations could have been caused by irregularities associated with EPBs. The TEC behavior that accompanied the scintillation reinforced the hypothesis that this mid-latitude scintillation was caused by EPBs reaching abnormally high apex heights (> 2600 km) and magnetic dip latitudes (> 28^°). Considering that scintillations were detected at dip latitudes corresponding to 1400 km apex heights at around 23:00 UT and at 2600 km apex heights at around 02:00 UT, one can estimate that an EPB would have to move vertically (over the equator) at approximately 111 m/s (on average). This vertical velocity is in good agreement with expectations of EPB rising velocities (Abdu et al. 1983).

The deployment and observations provided by the ScintPi 3.0 monitors are timely as GOLD observations of the nighttime F-region ionosphere in the American sector are currently available. Most of the studies reporting the detection of extreme EPBs relied on ground-based measurements and, consequently, had limitations in either spatial resolution or coverage. Observations based on ground-based TEC receivers, for instance, had limitations due to the sparse distribution of sensors and a lack of measurements over the oceans. GOLD observations, as presented here, represent a new contribution in the detection and understanding of the extreme EPBs. GOLD images are well-suited to aid the interpretation of the source of mid-latitude scintillation since it wide coverage over continents and oceans allows adequate comparison with the scintillation monitor observations.

The upper panels of Fig. 3 show a sequence of the OI 135 nm emission measurements made by GOLD between March 13 23:40 UT and March 14 00:22 UT. For comparison purposes, the lower panels show GOLD images for the following night (March 14–15, 2022). The solid red line indicates the location of the magnetic equator.

Fig. 3

Upper panels (a–c): OI 135 nm images measured by GOLD on March 13–14, 2022. The images exhibit extreme EPBs reaching latitudes larger than that of Puerto Rico (green X). Lower panels (d–f): OI 135 nm images measured by GOLD on March 14–15, 2022. The observations on March 14–15 are shown for comparison purposes and exhibit more typical latitudinal extents of the EIA and the EPBs

The images reveal regions of enhanced emission located at off-equator latitudes. These emissions indicate the location of the EIA peaks. The dark streaks of reduced emission nearly aligned with the magnetic meridian are signatures of EPBs. More importantly, the images reveal that, during the night of March 13–14, the EIA region was expanded to abnormally high latitudes. For reference, images for March 14–15 (lower panels) show an example of EIA that is representative of typical conditions, that is, with peaks that are more compact in latitude and closer to the magnetic equator. In addition to an expanded EIA, GOLD images reveal that EPBs reached abnormally high latitudes on March 13–14. For instance, the image on panel (a) shows the occurrence of enhanced background emissions (ionospheric densities) around Puerto Rico. In the sequence, at 00:10 UT and 00:22 UT of March 14, the images show EPBs above Puerto Rico and beyond, respectively. The enhanced background F-region densities and the EPBs may also explain the severe L-band scintillation observed by the monitors over Puerto Rico (e.g., Basu et al. 1988). Enhanced background densities lead to density perturbations (ΔN) with large amplitudes and, potentially, to more intense amplitude scintillation (Yeh and Liu 1982). More recent studies, however, pointed out that variations in the irrregularity spectrum might also contribute to variations in the magnitude of L-band scintillation. Bhattacharyya et al. (2017, 2019) show that irregularities with a “shallow” spectrum would, in combination with a high ambient plasma density around the EIA, produce strong scintillation on the L-band. According to their results, this "shallow" spectrum would be more likely to be associated with topside EPBs. In the event discussed on this work both conditions are present, i.e., large ambient plasma density and EPBs reaching very high topside altitudes.

As mentioned earlier, GOLD images allow a more direct comparison between the scintillation measurements and the underlying F-region conditions. An example of such comparison is presented in Fig. 4, where scintillation measurements made within ± 10 min of the GOLD image (00h10-00h25 UT) are exhibited. More specifically, Fig. 4 shows the S₄ values measured by the ScintPi 3.0 monitors overlaid on the GOLD OI 135 nm images. For this comparison OI emission intensities are represented by a grayscale colormap. The size and color of each scintillation value represented in the figure are related to its amplitude. It can be seen that regions of enhanced S₄ are well correlated with the EPBs (darkest bands) in the GOLD image. The comparison confirms, unambiguously, that the scintillation events were caused by extreme EPBs reaching the latitudes of Puerto Rico and beyond.

Fig. 4

Collocated GOLD OI 135 nm and ground-based scintillations observations made on March 14, 2022. GOLD images are for 00:10–00:25 UT. Scintillation measurements are for ± 10 min within the time of the GOLD image

On the conditions leading to extreme EPBs

In the previous sections, new TEC and scintillation measurements made in Puerto Rico were presented and a unusual occurrence of an intense mid-latitude L-band scintillation event over dip latitudes > 28° was discussed. Using simultaneous and collocated GOLD images, it was possible to demonstrate that the scintillation events were caused by an exteme EPB. This section presents a possible explanation for the abnormally high rise of the EPBs observed on March 13–14, 2022.

The explanation follows the hypothesis put forward by Mendillo et al. (2005) and the numerical experiment presented by Krall et al. (2010). Mendillo et al. (2005) argued that EPBs stop rising when the flux-tube integrated electron density inside the EPB matches the flux-tube integrated density of the surrounding background ionospheric plasma. Krall et al. (2010) evaluated this proposition using numerical simulations of EPBs performed by the Naval Research Laboratory SAMI3/ESF code (Huba et al. 2008) and found evidence supporting the Mendillo et al. (2005) hypothesis.

GOLD observations not only provide information about the occurrence and extent of EPBs, but also about the background F-region plasma conditions under which they appeared. On the night of March 13–14, 2022 the observations show an unusually wide EIA with the background density peaks extending to latitudes much higher than typically observed, especially over the northern hemisphere (please, compare GOLD observations for March 13–14 and March 14–15 in Fig. 3). The expanded EIA and large F-region electron densities at mid-latitudes on March 13–14 indicate height profiles of flux-tube integrated densities scale heights that are larger than those of most days. As a consequence, EPBs would have to rise to higher altitudes to reach a region where their internal flux-tube integrated density matches that of the background ionospheric plasma. Therefore, the observations indicate conditions favoring the abnormally high rise of EPBs, as proposed by Mendillo et al. (2005).

While the focus of this work is to present experimental evidence that extreme EPBs can cause scintillation over mid-latitudes and evaluate the F-region conditions favoring the high rise of the EPBs, some insight on the geospace conditions leading to the observed F-region morphology (i.e., the expanded EIA) is also offered. In that respect, it must be pointed out that a two-step magnetic storm (Kamide et al. 1998) was under development on March 13. Therefore, the expanded EIA occurred during a period that may be described as geomagnetically disturbed, when the low-latitude plasma transport might be enhanced. Figure 5 presents two panels with information about the interplanetary magnetic field (Bz), the SYM/H index, and the interplanetary electric field (Ey) for the period between March 12 and 15, 2022. Please observe that this figure is showing more days only to highlight the geomagnetic changes during the period of interest (March 13–14). The upper panel exhibits the interplanetary magnetic field (black) and the SYM/H (red). A sudden storm commencement, following a southward Bz turning, started around 12:00 on March 13. Subsequently, additional oscillations in Bz were followed by decreases in the SYM/H (increases in the ring current) reaching values around -114 nT, which, according to the “classic” definition (e.g., Sugiura and Chapman 1960; Loewe and Prölss 1997) indicate a strong storm.

Fig. 5

Geomagnetic conditions over some days around the extreme EPB event. Upper panel: Interplanetary magnetic field (Bz) and SYM/H index revealing a storm onset around 12:00 UT on March 13. Lower panel: Interplanetary electric field (Ey) showing enhancements in magnitude during the geomagnetic storm period

The lower panel shows the interplanetary electric field (Ey) reaching magnitudes larger than 10 mV/m. Blue/red colors were used to indicate dawn-to-dusk/dusk-to-dawn orientation of the Ey. The green rectangular region corresponds to the interval of time presented in Fig. 4 (00:10–00:25 UT on March 14, 2022). Two mechanisms could have worked separately or conjointly, the disturbance dynamo (Blanc and Richmond 1980) and the disturbance electric fields (Senior and Blanc 1984).

Since the storm onset occurred several hours before the dusk, the disturbance dynamo effects had time to alter the equatorial electrodynamics, leading to an enhanced uplift of the plasma and contributing to the expansion of the EIA crests. However, an intense increase in Ey was noticed a few minutes before the extreme EPB event presented in Figs. 3 and 4 as well. According to Kelley et al. (2003), the “efficiency” of the so-called penetration electric field would be about ~ 6.6% of Ey. The Ey reached 12.21 mV/m at 22:49 UT on March 13, 2022, and, therefore, could have caused a penetration electric field of about 0.81 mV/m. If the magnetic field intensity at the equatorial region corresponding to that magnetic field line apex is considered (20953 nT) and assuming a purely E/B vertical drift (i.e., no contribution from meridional winds), that would lead to an additional upward velocity of ~ 38.46 m/s. Therefore, penetration electric fields could also have been responsible for the enhanced redistribution of plasma to higher latitudes, leading to the expanded EIA observed on March 13–14, 2022. Rajesh et al. (2021) presented one example of such mid-latitude plasma density enhancement under the combination of geomagnetic storm induced neutral winds and increased fountain effect due to penetration electric fields action. Maruyama et al. (2005) used simulation to explore how the merged contribution from the disturbance dynamo and prompt penetration electric fields could potentially lead to increased eastward electric field in the dusk sector, therefore, causing more poleward EIA crests.

More specific discussions about the effects of geomagnetically disturbed conditions on the low and mid-latitudes can be found by Blanc and Richmond (1980), Abdu, (1995, 1997, 2012), Kelley et al. (2003), Huang et al. (2007b), and Fejer et al. (2008, 2021).

Conclusion

Previous studies discussing the detection of ionospheric irregularities and/or scintillation events over mid-latitudes proposed distinct explanations for these events (e.g., Mendillo et al. 1997; Kelley, et al. 2000; Martinis et al. 2015; Kil et al. 2016; Hysell et al. 2016). Kil et al. (2016) pointed out that the observational gap in the region between equatorial and mid-latitudes could be one of the main obstacles for a more conclusive determination of the sources of irregularities and scintillation observed at mid-latitudes.

This work presents new joint ground- and space-based observations showing unequivocal evidence of severe L-band ionospheric scintillations and large TEC depletions over low-to-mid latitudes caused by extreme EPBs, that is, EPBs reaching extremely high magnetic apex heights.

Measurements made by ground-based ionospheric scintillation and TEC monitors deployed in Puerto Rico provided information indicating that ionospheric irregularities and scintillation originated at low latitudes and propagated, subsequently, to mid-latitudes. Simultaneous imaging of the ionospheric F-region from equatorial to mid-latitudes provided by the GOLD mission confirmed, conclusively, that the ionospheric irregularities and scintillation observed over Puerto Rico and higher latitudes were indeed caused by extreme EPBs. These observations are in good agreement with previously proposed theories and numerical simulations. The ground-based and satellite measurements show that plasma bubbles reached apex heights exceeding 2600 km and magnetic dip latitudes beyond 28^°. GOLD observations also reveal an abnormal expansion (in latitude) of the EIA. Finally, GOLD shows enhanced background F-region densities at mid-latitudes favoring the occurrence of intense L-band scintillation when topside EPBs reach that region.