--- title: "May 2024 solar superstorm drew 85% of its ring current ions from Earth; Arase measured a 40% field drop" url: https://badiyaa.com/may-2024-solar-storm-earth-oxygen-ions-arase/ published: 2026-11-14T07:04:00+00:00 modified: 2026-11-14T07:04:00+00:00 section: Science publisher: Badiyaa --- # May 2024 solar superstorm drew 85% of its ring current ions from Earth; Arase measured a 40% field drop During the May 2024 solar superstorm, about 85% of ring current ions were oxygen from Earth's ionosphere, Nagoya University's Arase satellite study found. Our star lit the fuse, but Earth may have supplied most of the ammunition. During the giant May 2024 geomagnetic storm, about 85 percent of the ions in the planet’s ring current were oxygen from Earth’s own upper atmosphere, not solar particles, according to measurements by Japan’s Arase satellite analyzed by a team at Nagoya University. The study, “Extreme dominance of Earth-origin heavy ions in the intense ring current near the Earth during the May 2024 super geomagnetic storm,” appeared in Science Advances on 26 June 2026. Lead author Naritoshi Kitamura is a designated assistant professor at Nagoya’s Institute for Space-Earth Environmental Research (ISEE). ## How Arase caught the storm from inside the ring current The ring current is a vast belt of charged particles, mostly oxygen and hydrogen ions, that drifts around Earth thousands of kilometers above the equator. As those ions circle, they carry an electric current whose magnetic field partly cancels Earth’s own. Ground stations read that weakening as the size of a storm. Scientists have argued for decades about where those ions come from. One source is the solar wind, the stream of particles flowing off our star. The other is the ionosphere, the electrically charged top layer of Earth’s atmosphere. Because the May 2024 storm was driven by unusually dense solar wind, some researchers expected a large solar share. Arase, launched in 2016 and operated by the Japan Aerospace Exploration Agency (JAXA), flies through exactly that region and can sort ions by mass and energy. By luck of its orbit, it passed through twice: once in the storm’s opening hours and again close to its strongest point. “This is the first simultaneous observation of ring current ions and solar wind during a storm this large, and the data was clear—approximately 85% of ions were oxygen from Earth’s own ionosphere,” Kitamura said in the Nagoya University announcement. ## Why heavy oxygen ions could make a storm stronger Mass is the key. An oxygen ion weighs about 16 times as much as a hydrogen ion, the main particle in the solar wind. Heavier ions moving at similar energies carry the ring current differently, and the researchers suggest that this flood of oxygen helped intensify the magnetic disturbance and pulled the ring current’s peak unusually close to the planet. Arase also recorded how deep the effect reached. “Near the peak of the storm, Arase detected a 40% decrease in magnetic field intensity at roughly 16,000 kilometers above Earth, and much closer to Earth than similar large decreases previously documented,” Kitamura said. At the same spot, the number of high-energy electrons that normally circle there dropped. The storm, called the Gannon storm or Mother’s Day storm, struck on 10 and 11 May 2024. It pushed the SYM-H index, a minute-by-minute gauge of ring current strength, to minus 518 nanotesla, the second-largest value since 1981, the team reports. The [Wikipedia account of the May 2024 solar storms](https://en.wikipedia.org/wiki/May_2024_solar_storms) notes that auroras were seen as far south as the Florida Keys and that it was the strongest storm to hit Earth since March 1989. ## What one satellite pass can and cannot settle The result rests on observations from one spacecraft during one storm, so it shows what happened in May 2024 rather than a rule for every superstorm. The team frames the heavy-ion link as a likely contributor, using the word “may,” and says it has not established whether the warped magnetic field caused the electron loss Arase saw. That question, the release says, warrants further investigation. The finding still points to a gap in forecasting. Space weather models mainly read conditions in the solar wind to predict how strong a storm will get. If Earth’s upper atmosphere can supply most of the ions, the state of the ionosphere also needs to be in the forecast. For aurora watchers, Badiyaa covered an October [northern lights forecast for a minor G1 storm](https://badiyaa.com/northern-lights-forecast-g1-storm-october/), and the [Parker Solar Probe’s findings on the solar wind’s magnetic twist](https://badiyaa.com/parker-solar-probe-solar-wind-magnetic-twist/) cover the solar side. The Nagoya team’s next step is FACTORS, a proposed two-satellite mission being prepared for JAXA’s upcoming proposal round to measure how oxygen escapes from the atmosphere into space. ## Further reading - [Wikipedia: May 2024 solar storms](https://en.wikipedia.org/wiki/May_2024_solar_storms) *Image: NASA/Mara Johnson-Groh, Public domain via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*