Geomagnetic superstorm Gannon reduced Earth's protective plasmosphere

Geomagnetic storms are not uncommon, but most of them pass without any special consequences. Last year, the Earth experienced the most powerful geomagnetic storm in more than 20 years, known as Storm Hanno or "Mother Storm." The phenomenon caused serious problems, including failures in GPS, satellite operation, and power supply. This was reported by Popular Science magazine on November 20.

The researchers conducted a thorough analysis of the data collected by various instruments around the world. One of the main sources of information was the Arase satellite, launched by the Japanese Space Agency (JAXA) in 2016. He was in an ideal position to observe changes in the plasmasphere when Storm Gannon passed through the planet.

"We monitored changes in the plasmosphere using the Arase satellite and used ground-based GPS receivers to monitor the ionosphere of the source of charged particles replenishing the plasmosphere. Both layers showed us how dramatically the plasmosphere was reduced and why the restoration took so long," said Atsuki Shinbori, professor of environmental monitoring at the Institute of Space and Earth Studies at Nagoya University.

The Earth's plasmosphere plays a key role in blocking dangerous cosmic radiation, which is constantly coming from the Sun and from deep space. Without it, satellites and navigation systems such as GPS would not be able to work for a long time.

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Storm Gannon demonstrated how a serious geomagnetic impact can affect the restoration of the plasmosphere, slowing down the process due to changes in the chemical composition of the atmosphere. The outer boundary of the plasmasphere usually extends about 43.8 thousand km above the Earth, but within nine hours it shrank to 8965 km, which is about five times less than its original width. It took four days for the plasmasphere to recover.

"We found that the Storm initially caused intense heating near the pluses, but then it led to a sharp drop in the concentration of charged particles in the ionosphere, which slowed its recovery. This prolonged disruption could affect GPS accuracy, interfere with satellite operations, and make space weather forecasting more difficult," Sinbori added.

It usually takes one to two days for the plasmasphere to recharge after most solar storms, but Gannon described a unique phenomenon called a "negative storm." According to Sinbori, this slowed the recovery by changing the chemical composition of the atmosphere and stopping the flow of particles through the plasmosphere. This phenomenon has never been observed before.

With the data obtained, scientists can more accurately predict how the plasmasphere will recover after strong geomagnetic storms, which will help develop more effective measures to protect satellites and navigation systems from similar events in the future.

Earlier, on November 19, Lisa Upton, a heliophysicist from the Institute of Southwestern Studies, spoke about the effects of auroras on the Sun. It was noted that solar activity has been increasing and decreasing for 11 years and is estimated by the number of sunspots. The specialist shared that she expects a further decrease in the number of relevant spots.

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