An international team led by researchers from the Institute of Ionosphere at the National Technical University «Kharkiv Polytechnic Institute» has revised one of the key tenets of the classical theory of storms in the Earth’s charged-particle environment—the ionosphere. The scientists have demonstrated that the number of charged particles can increase even during the descent of the ionosphere, not just during its ascent. This discovery will help generate more accurate forecasts of ionospheric storms and, consequently, reduce the risk of disruptions to satellite navigation systems and global radio communication channels, which are a critical component of military and civilian infrastructure. The results of the study were published in the international peer-reviewed journal «Space Weather» (U.S.). From the Institute of the Ionosphere, Director Dmytro Kotov and researchers Maryna Reznichenko, Oleksandr Bohomaz, and Ihor Domnin participated in the study. Their partners included colleagues from leading research centers in the U.S., Poland, and Spain, as well as from the National Antarctic Scientific Center of the Ministry of Education and Science of Ukraine and the Radio Astronomy Institute of the National Academy of Sciences of Ukraine.
The Earth’s atmosphere consists not only of neutral atoms and molecules. Solar radiation ionizes some of them, creating free electrons and ions that form the ionosphere—a medium of charged particles surrounding the Earth. Importantly, the ionosphere has a significant effect on the propagation of radio waves. «Within a certain range of radio frequencies (so-called short waves), the ionosphere can act as a mirror, reflecting radio waves directed at it,» notes Dmytro Kotov, director of the Institute of the Ionosphere. «This makes it possible to establish radio communication with any point on the globe without satellites. Furthermore, this reflection from the ionosphere makes so-called over-the-horizon radar possible—this is when you can literally look beyond the horizon and see aircraft or ballistic missiles at distances of up to 3,000 km. The range of conventional radar systems is ten times shorter, as it is limited by the curvature of the Earth. Incidentally, the Canadian government has just signed a contract to purchase the JORN over-the-horizon radar system to monitor russian and Chinese activities in the Arctic. A total of six and a half billion U.S. dollars has been allocated for this project. It is important to remember that for such unique systems to operate reliably, accurate forecasts of the state of the ionospheric mirror and its disturbances are essential.»
The ionosphere no longer reflects even shorter radio waves (such as those used by navigation systems like GPS)—they pass right through it. However, the ionosphere still affects radio waves in this case as well, and its effect is negative: the ionosphere alters the phase of radio signals. And if the actual state of the ionosphere differs from forecasts, the coordinates of objects can be estimated with significant errors. «Here’s a recent example from civilian life,» says Dmitry Kotov. «In May 2024, a powerful solar storm triggered a severe storm in the ionosphere. The number of charged particles fluctuated significantly during the storm. As a result, errors in determining the coordinates of objects across the United States reached 70 meters. At that time, the planting season was underway, and modern agricultural equipment plants crops «to the line» using GPS. It’s easy to see that the misalignment of rows while planting farm fields reached those same 70 meters, and the misalignment fluctuated throughout the storm. Much of the crop had to be replanted, and precious time was lost. According to confirmed data, due to the lack of a reliable forecast for this ionospheric storm, losses incurred by American farmers amounted to approximately $500 million.»
Such examples demonstrate that forecasting ionospheric storms is no less important for humanity than forecasting hurricanes, floods, and other natural disasters. That is why experts from around the world have been working on ionospheric storm forecasts for many decades. However, the accuracy of these forecasts remains low. The reason is that a complete scientific understanding of how ionospheric storms develop has not yet been established. This is particularly true for so-called prolonged positive ionospheric storms – a phenomenon that leads to an increase in the number of charged particles over certain regions of the globe for many hours or even days. New findings, recently obtained by researchers at the Institute of the Ionosphere at NTU «KhPI» in collaboration with colleagues from the U.S., Poland, and Spain, have changed scientists’ understanding of this least-studied phenomenon. «We have proven that Gerd Pröls’s classical theory of positive ionospheric storms does not always hold true,» explains Dmytro Kotov. «According to his theory, a necessary condition for an increase in the number of charged particles during a storm is the upward movement of the ionosphere: the greater the altitude, the longer the charged particles survive, and thus, over time, their number increases. But we have demonstrated that the number of charged particles can increase even when the ionosphere is moving downward, where the lifetime of charged particles decreases sharply.»
The results of a study conducted by a team from the Institute of the Ionosphere—comprising Director Dmytro Kotov and researchers Maryna Reznichenko, Oleksandr Bohomaz, and Ihor Domnin – in collaboration with international partners have been published in the prestigious international journal «Space Weather» (https://agupubs.onlinelibrary.wiley.com/doi/10. 1029/2026SW005028), which is known for its strict requirements regarding the novelty and practical impact of scientific findings. It is worth noting that the team from the Institute of the Ionosphere at NTU «KhPI» is the first in Ukraine to lead a publication in this journal, which has been in circulation for 23 years.
«We are proud that our results will help create more accurate forecasts of ionospheric storms,» says Dmytro Kotov. «It was also incredibly interesting to work with the reviewers at «Space Weather». Just like us, they were accustomed to the classical theory of ionospheric storms. It was a real creative challenge for us to prove that a phenomenon once considered impossible actually exists.»
Note:
The Ionosphere Research Institute, National Technical University «Kharkiv Polytechnic Institute» is a leading scientific institution in Ukraine that conducts fundamental and applied research on near-Earth space and space weather using ground-based and satellite-based methods, as well as mathematical modeling. Research is conducted in close collaboration with scientific centers in the U.S., the EU, and Japan. The Institute is a member of the European Space Agency’s SAWA research mission (SAWA: Scientists from Kharkiv Polytechnic Institute are participating in a space mission; details of the research—Suspilne Kharkiv) and takes part in Antarctic expeditions (XXIX Ukrainian Antarctic Expedition—Wikipedia). The Institute’s Ionosphere Observatory, located near the town of Zmiyiv, is a scientific facility that constitutes a national treasure of Ukraine. In 2026, the Ionospheric Observatory became part of Eric Lucito’s international photographic research project, the results of which were published in outlets such as The Guardian and New Scientist. The Institute’s research findings are regularly published in leading international scientific journals, including Geophysical Research Letters (in the top 0.5% of Scopus journals), «Acta Astronautica» (NTU «KhPI» – a participant in the European space mission SAWA for studying space weather – National Technical University «Kharkiv Polytechnic Institute»), «Space Weather», and others. Thanks to these publications, in 2025, NTU «KhPI» ranked first among Ukrainian universities in the most prestigious international Nature Index ranking in the «Earth and Environmental Sciences» category.
«Space Weather» is an international peer-reviewed journal of the American Geophysical Union, founded in 2003. The journal publishes new scientific findings that help improve our understanding of space weather phenomena, refine their forecasting, and mitigate risks to satellite navigation, communications, energy, and other technologies.
The article was published at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2026SW005028. Co-authors include researchers from the University of Alabama in Huntsville, the Massachusetts Institute of Technology, Johns Hopkins University (U.S.), the Space Research Center of the Polish Academy of Sciences (Poland), the Polytechnic University of Catalonia (Spain), as well as the National Antarctic Scientific Center of the Ministry of Education and Science of Ukraine and the Radio Astronomy Institute of the National Academy of Sciences of Ukraine.