Shedding Light on Space Weather Events on Earth’s Nightside

The nightside of the Earth can’t escape the effects from the sun’s storms. 

In a new study, UNH researchers found that solar storms boost the jets of charged particles on the side of Earth opposite the sun, leading to more plasma streaming toward the planet that can put satellite technology and power grids at risk. 

The research, led by UNH Ph.D. student Anusree Devanandan, examined fast, short-lived jets of charged particles known as bursty bulk flows. These jets form in the tail of Earth’s magnetic shield, in a hot and relatively dense layer of charged particles called the plasma sheet. Although bursty bulk flows have been observed for decades, this research is the first to compare how they behave during geomagnetic storms versus quieter, non-storm periods. 

“We finally have this huge dataset we can examine for patterns to better understand these intense, Earthward-traveling plasma jets,” Devanandan says. “We’re just now scratching the surface of their behaviors during geomagnetic storms.”

For this study, Devanandan compiled 30 years of plasma data from the Geotail spacecraft — a partnership between NASA and Japan’s Institute of Space and Astronautical Science that recorded magnetic reconnection events in the magnetotail. Magnetic reconnection is a phenomenon where the Earth’s magnetic field lines suddenly reconfigure and release enormous amounts of energy in the process. Bursty bulk flows carry about 70% of the plasma ‘exhaust’ from reconnection events in the magnetotail back toward the Earth, so it’s a conduit for the magnetic flux that can impact our technology. 

Devanandan said she was surprised to find that bursty bulk flows move at similar velocities whether or not there’s a geomagnetic storm occurring, but the background conditions during storms — like stronger magnetic fields and hotter plasma — enhance the properties and behaviors of the jets: they can carry more mass and energy with them as they hurtle closer to our planet. 

Devanandan’s work was funded by NASA’s Center for Geospace Storms, of which UNH is a contributing institution. She spent time at the lead institution for the center, the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, collaborating with other researchers there for this project. “It was a wonderful opportunity to work with highly experienced researchers and learn from them,” she notes.

“The collaboration with team members at the Center for Geospace Storms has been a key part of this work,” affirms Amy Keesee, UNH professor of physics. Keesee is Devanandan’s Ph.D. advisor, a co-author on this study, and the Broadening Impacts Section Head for the Center for Geospace Storms. “This work highlights the benefits of large, collaborative science centers that provide opportunities for cutting edge science and STEM workforce development.”