Geomagnetic storms, driven by coronal mass ejections that flood near Earth space with energetic particles, temporarily boost upper atmospheric density. The added drag slows satellites, lowers altitudes, and shortens mission lifetimes. Managing these effects has become central to navigation, data links, and national security in low Earth orbit.
Using an advanced whole atmosphere model, the team finds that future storms of the same intensity will reach lower absolute peak densities than todays equivalents because the background will be thinner. Yet the relative jump from baseline to peak will be larger in a less dense environment.
"The way that energy from the Sun affects the atmosphere will change in the future because the background density of the atmosphere is different and that creates a different response," said NSF NCAR scientist Nicolas Pedatella, the lead author.
"For the satellite industry, this is an especially important question because of the need to design satellites for specific atmospheric conditions."
Unlike the warming lower atmosphere, carbon dioxide cools the rarefied air aloft. At high altitudes, CO2 more efficiently radiates heat to space rather than sharing it with neighboring molecules, yielding colder, thinner conditions that reshape how solar energy modifies the thermosphere and ionosphere during multiday storms.
The study examined the May 10-11, 2024 superstorm and simulated the same forcing for 2016 and for future solar-minimum years 2040, 2061, and 2084. Researchers applied the Community Earth System Model Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (CESM WACCM-X), running on the Derecho supercomputer at the NSF NCAR-Wyoming Supercomputing Center.
Assuming substantially higher future CO2 levels, model results indicate that peak stormtime densities in various upper atmospheric regions could be 20-50 percent lower later this century. Even so, where today's comparable events more than double density, future responses could nearly triple relative to immediately pre- and post-storm conditions.
The project, conducted with collaborators at Kyushu University in Japan and published in Geophysical Research Letters, underscores the need to assess different storm types and solar cycle phases. "We now have the capability with our models to explore the very complex interconnections between the lower and upper atmosphere," he said. "It's critical to know how these changes will occur because they have profound ramifications for our atmosphere."
Research Report:Impact of Increasing Greenhouse Gases on the Ionosphere and Thermosphere Response to a May 2024-Like Geomagnetic Superstorm
Related Links
National Center for Atmospheric Research
Space Technology News - Applications and Research
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