As seen across North America at sometimes surprisingly low latitudes, brilliant auroral displays provide evidence of solar activity in the night sky. More is going on than the familiar visible light shows during these events, though: When aurora appear, the Earth’s ionosphere is experiencing an increase in ionization and total electron content (TEC) due to energetic electrons and ions precipitating into the ionosphere.
One extreme auroral event earlier this year (May 10–11) was the Gannon geomagnetic “superstorm,” named in honor of researcher Jennifer Gannon, who suddenly passed away May 2. During the Gannon storm, both MIT Haystack Observatory researchers and citizen scientists across the United States observed the effects of this event on the Earth’s ionosphere, as detailed in the open-access paper “Imaging the May 2024 Extreme Aurora with Ionospheric Total Electron Content,” which was published Oct. 14 in the journal Geophysical Research Letters. Contributing citizen scientists featured co-author Daniel Bush, who recorded and livestreamed the entire auroral event from his amateur observatory in Albany, Missouri, and included numerous citizen observers recruited via social media.
Citizen science or community science involves members of the general public who volunteer their time to contribute, often at a significant level, to scientific investigations, including observations, data collection, development of technology, and interpreting results and analysis. Professional scientists are not the only people who perform research. The collaborative work of citizen scientists not only supports stronger scientific results, but also improves the transparency of scientific work on issues of importance to the entire population and increases STEM involvement across many groups of people who are not professional scientists in these fields.
Haystack collected data for this study from a dense network of GNSS (Global Navigation Satellite System, including systems like GPS) receivers across the United States, which monitor changes in ionospheric TEC variations on a time scale of less than a minute. In this study, John Foster and colleagues mapped the auroral effects during the Gannon storm in terms of TEC changes, and worked with citizen scientists to confirm auroral expansion with still photo and video observations.
Both the TEC observations and the procedural incorporation of synchronous imagery from citizen scientists were groundbreaking; this is the first use of precipitation-produced ionospheric TEC to map the occurrence and evolution of a strong auroral display on a continental scale. Lead author Foster says, “These observations validate the TEC mapping technique for detailed auroral studies, and provided groundbreaking detection of strong isolated bursts of precipitation-produced ionization associated with rapid intensification and expansion of auroral activity.”
Haystack scientists also linked their work with citizen observations posted to social media to support the TEC measurements made via the GNSS receiver network. This color imagery and very high TEC levels lead to the finding that the intense red aurora was co-located with the leading edge of the equator-ward and westward increasing TEC levels, indicating that the TEC enhancement was created by intense low-energy electron precipitation following the geomagnetic superstorm. This storm was exceptionally strong, with auroral activity centered relatively rarely at mid latitudes. Processes in the stormtime magnetosphere were the immediate cause of the auroral and ionospheric disturbances. These, in turn, were driven by the preceding solar coronal mass ejection and the interaction of the highly disturbed solar wind with Earth's outer magnetosphere. The ionospheric observations reported in this paper are parts of this global system of interactions, and their characteristics can be used to better understand our coupled atmospheric system.
Co-author and amateur astronomer Daniel Bush says, “It is not uncommon for ‘citizen scientists’ such as myself to contribute to major scientific research by supplying observations of natural phenomena seen in the skies above Earth. Astronomy and geospace sciences are a couple of scientific disciplines in which amateurs such as myself can still contribute greatly without leaving their backyards. I am so proud that some of my work has proven to be of value to a formal study.” Despite his modest tone in discussing his contributions, his work was essential in reaching the scientific conclusions of the Haystack researchers’ study.
Knowledge of this complex system is more than an intellectual study; TEC structure and ionospheric activity are of serious space weather concern for satellite-based communication and navigation systems. The sharp TEC gradients and variability observed in this study are particularly significant when occurring in the highly populated mid latitudes, as seen across the United States in the May 2024 superstorm and more recent auroral events.
