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** What is a geomagnetic storm? What impact does geomagnetic storms have on our lives? With these questions in mind, the reporter interviewed Luo Xiaomin, associate professor at the School of Geography and Information Engineering of China University of Geosciences (Wuhan). Luo Xiaomin has been engaged in research on the impact of geomagnetic storms on GNSS (Global Navigation Satellite System) satellite positioning in recent years. **

Geomagnetic storms will be more frequent this year and next

After paying attention to the geomagnetic storm warning news released by the China Meteorological Administration, Luo Xiaomin's research team also collected relevant geomagnetic activity data. Judging from the geomagnetic activity Kp index released by the Space Environment Prediction Center of the Chinese Academy of Sciences, the maximum value of the Kp index on March 24 reached 8, which is a severe magnetic storm level. The Kp index ranges from 0 to 9. Generally, the larger the Kp value, the stronger the geomagnetic storm.

Geomagnetic storms originate from solar activity and usually refer to disturbances in the Earth's magnetic field caused by the interaction of the increasing speed or density solar wind and the Earth's magnetic field. The activity of the sun has a certain periodic rule, and the frequency and intensity of occurrence are also regular to follow. Luo Xiaomin introduced that the solar activity cycle is about 11 years and is now in the 25th solar activity cycle. This cycle started in December 2019 and is expected to peak in 2024 - 2025. The more active the sun is, the more severe the disturbance to the Earth's magnetic field is usually, so geomagnetic storms will be more frequent this year and next.

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Luo Xiaomin (center) and his team

Geomagnetic storms affect carrier pigeon identification direction

In response to rumors on the Internet that "geomagnetic storms cause drowsiness", Luo Xiaomin explained that the impact of geomagnetic storms on the human body is actually very small. During geomagnetic storms, the airborne radiation flying across the polar region will increase several times compared to the magnetic quiet day, but the dose of this radiation is about tens to one-hundredth of the national safety standard, and has little impact on the human body. He said that geomagnetic storms mainly affect power grids and pipelines, low-orbit satellites, civil aviation, carrier pigeon release, etc. The interaction between magnetic lines and metal pipelines during geomagnetic storms will form induced currents, threatening the safety of power grid equipment.

According to reports, a geomagnetic storm in March 1989 damaged the power grid system in Quebec, Canada, causing normal power supply to most areas to resume nine hours later. For low-orbit satellites, atmospheric drag caused by geomagnetic storms will cause the orbital altitude of low-orbit satellites to decrease, which will have a certain impact on the normal operation of low-orbit satellites. In February 2022, due to atmospheric drag caused by geomagnetic storms, 38 of the 49 "Star Chain" satellites launched by Space Exploration Technologies Corporation on the 3rd of that month were damaged.

Geomagnetic disturbances during geomagnetic storms will affect the ability of carrier pigeons to identify directions, resulting in the inability of carrier pigeons to return home smoothly. According to reports, during the geomagnetic storm in April 2015, only about 600 of the more than 27000 carrier pigeons released successfully returned to their nests.

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Flare and coronal mass ejections observed by SOHO satellite on March 23, 2024.

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Geomagnetic storms affect GNSS positioning reliability

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