We present a dataset of 35,483 unique 1 minute periods (∼591 h) of quasi-perpendicular and quasi-parallel magnetosheath MMS classifications manually reviewed with the help of citizen scientists. This dataset spans a variety of representative solar wind conditions sampled over the course of 8 years of data on the dayside. We identify 7,697 high likelihood quasi-parallel magnetosheath minute intervals and an additional 2,315 moderate likelihood quasi-parallel intervals. Within this dataset, we also identify 2,677 temporal transitions between quasi-perpendicular and quasi-parallel magnetosheath at 1-min resolution. This rich dataset can be used to perform statistical studies of these two populations and to train machine learning models.
During geomagnetic storms, the inner portion (L < 7) of Earth’s magnetosphere is flooded with hot (∼keV energy range) ions and electrons from the plasma sheet. These particles differentially drift, creating a variety of electric current systems collectively known as the stormtime ring current. It is of such importance that it is often considered to be the defining element of intense space storms. This review presents evidence of the importance of the stormtime inner magnetospheric electric current systems for the development of intense geomagnetic activity, especially regarding magnetopause shadowing of the outer radiation belt, altering the nightside ionospheric convection pattern, structuring the plasmapause, and inhibiting subsequent injections from the tail.
The sporadic E (Es) layer is a transient electron-density irregularity in the partially ionized E-region whose occurrence strongly modulates VHF radio propagation and can interfere with aviation navigation and maritime communications. Building on Deacon et al., who demonstrated the feasibility of detecting Es with amateur-radio WSPR (Weak Signal Propagation Reporter) signals, this study scales the approach to a full year using global WSPR data from 2021 (early ascending phase of solar cycle 25; annual mean sunspot number 29.6) and the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm for automated Es detection. After distance filtering (750–2,500 km) and band screening (28/50 MHz), 1.49 million valid reports were extracted from approximately 830 million raw records, yielding 27,253 window-level Es detections. Summer (May–August) produced 19,002 detections versus 6,146 in winter (November–February), a ratio of 3.09 consistent with classic mid-latitude Es climatology, with additional evidence of Southern Hemisphere summer activity (summer-to-winter ratio 5.6:1 in the 25–35°S band). Spatial hotspots were identified in three mid-latitude belts: Europe (35–55°N), East Asia (25–45°N) and North America (30–50°N). Cross-validation against the Juliusruh ionosonde yielded a probability of detection of 57% (800 km, foEs > 3 MHz). As a crowdsourced measurement technique, the method offers broader spatial coverage than vertical-incidence sounder networks and provides an effective supplement to existing Es and ionospheric-irregularity monitoring systems.
Modern technological society is highly vulnerable to extreme geomagnetic storms, yet the terrestrial upper limit of such events remains poorly constrained because continuous instrumental geomagnetic records cover only a relatively short historical period. To extend this baseline, we quantitatively reconstruct the geomagnetic superstorm of September 1770 (termed Qianlong XXXV storm) using systematically documented auroral observations preserved in Chinese regional chronicles. These historical records indicate that the auroral oval expanded to a magnetic latitude as low as 20.40°N at the ionospheric height, implying an exceptionally intense magnetospheric disturbance. From this equatorward auroral boundary, we derive a best-estimate Disturbance Storm Time (Dst) index of −1,319 nT (95% Confidence Interval (CI): [−1,832, −1,066]), exceeding the reconstructed Dst intensity of the 1859 Carrington event (≈ −1,025 nT, 95% CI of [−1367, −853]) by approximately 30%. An extreme value statistical model suggests an order-of-magnitude recurrence interval of approximately 14,000 years for the Qianlong XXXV event, compared with approximately 1,400 years for Carrington-class storms. These results suggest that the Qianlong XXXV geomagnetic storm represent an important low-latitude benchmark for extreme solar–terrestrial disturbances. This potential benchmark provides a quantitatively constrained reference for testing the physical limits of modern infrastructure and the atmosphere of the Earth under the impact of catastrophic space weather.
Large geomagnetic storms often drive complex upper atmospheric and ionospheric disturbances with a broad range of spatial and temporal scales. We used Jicamarca Radio Observatory observations and complementary solar and geomagnetic field measurements to study the response of equatorial ionospheric electric fields to recent major and moderate geomagnetic storms. Our measurements near dusk and nearly steady southward interplanetary magnetic fields during 24 April 2023, 10–11 October 2024, and 16–17 May 2025 show very large-amplitude (more than 100 m/s), short-lived (less than 1 hour) upward vertical plasma drifts indicative of inductive prompt penetration electric fields. Recent Jicamarca measurements show several additional similar events. We suggest that these large bursty prompt-penetration drifts were driven by substorms associated with low-entropy magnetospheric bubbles and bursty bulk flows (BBFs). Our data indicate, in particular, that a magnetospheric substorm-driven prompt-penetration electric field drove a very large increase in the F layer height over Jicamarca near dusk on 10 October 2024 and the resulting very strong equatorial plasma bubbles extending to mid-latitudes. In this event, the upward drift reached in excess of 300 m/s, corresponding to an eastward electric field of more than 7 mV/m, the largest ever observed over Jicamarca. The Jicamarca measurements near dusk during the 16–17 May 2025 moderate magnetic storm show, for the first time, two large-amplitude, short-lived, substorm-associated, bursty prompt penetration drifts near dusk driving strong equatorial plasma irregularities. The early-night large-amplitude prompt perturbation drifts during these storms are not reproduced by the widely used Prompt Penetration Electric Field Model (PPEFM). Our and complementary observations highlight both the complex response of the low-latitude ionosphere to geomagnetic storms and the need for more extensive high-time-resolution global measurements for their better understanding.
