15.07.2024

The symmetry supports the idea that snappy magnetic field lines drive the storms

Dozens of space hurricanes (one illustrated) swirl at both of Earth’s magnetic poles each year, largely in summer months. The plasma cyclones may be driven by snappy magnetic field lines.

QING-HE ZHANG/SHANDONG UNIVERSITY

On Earth, hurricane season isn’t just surface level. The ionosphere, an upper layer of the atmosphere charged by solar radiation, also contains swirling storms of plasma dubbed “space hurricanes.” Scientists first described a space hurricane in 2021: It was a cyclone-shaped aurora, swirling for hours near Earth’s north magnetic pole and raining down electrons, rather than water, into the upper atmosphere.

Now, new research reveals that parallel space hurricanes swirl near the south magnetic pole as well.

An analysis of satellite data collected from 2005 to 2016 identified 259 space hurricane events in the Southern Hemisphere’s ionosphere, space physicist Sheng Lu of Shandong University in Weihai, China, and colleagues report June 25 in the Journal of Geophysical Research: Space Physics. That’s about 23 events per year on average, which is close to the rate that was previously estimated for the Northern Hemisphere. The team identified other symmetries too. For instance, space hurricanes in both hemispheres tend to occur in summer months.

The researchers suspect that the storms are driven by shifts in Earth’s magnetic field caused by the solar wind (SN: 8/18/17). This barrage of charged particles from the sun splits magnetic field lines­. When the lines reconnect, they roil ionized gas in the ionosphere, driving flows of electric current upward, the team suggests. Flows then bend and begin to spin, leaving an “eye” at the center. That proposed process would be akin to the rise of warm, humid air at the center of a tropical cyclone.

Quelle: ScienceNews