According to the China Meteorological Administration, significant geomagnetic activity is expected on March 24th, 25th, and 26th. On March 25th, there could be moderate to severe geomagnetic storms, with the activity likely to persist until the 26th.
Following this announcement, discussions about "geomagnetic storms" quickly surged on various social media platforms, prompting many to wonder if it will affect their daily work routines.
Some netizens have also mentioned that the geomagnetic storm has had various effects on their physical well-being:
So, what exactly is a geomagnetic storm? Does it really have various effects on our bodies? Actually, around December 1st last year, there was also a geomagnetic storm, and some astronomy enthusiasts even observed auroras in Beijing... Let's chat about it today!
Last December 1st, netizens captured the aurora in Beijing, as seen on Weibo.
Calling upon the primordial solar winds: The genesis of auroras and geomagnetic storms
Diagram illustrating the interaction between solar energetic particle flux (solar wind) and the Earth's magnetosphere.Why do auroras have different colors?
The vibrant colors of auroras are related to different atmospheric particles and luminescent processes, occurring at different altitudes.
For instance, the most common green aurora is emitted when oxygen atoms, excited to an excited state, rapidly return to their ground state, emitting light within a short duration (ranging from 1 to several seconds), typically at altitudes of 100 to 200 kilometers. Similarly, red auroras result from the emission of excited oxygen atoms returning to their ground state, but this process takes longer (from several tens of seconds to over a hundred seconds), during which any collision with other particles results in the loss of energy, preventing luminescence. Therefore, red auroras are more commonly observed at higher altitudes with lower particle densities, typically around 200 to 350 kilometers.
Generally, due to the sparse distribution of luminescent particles in the upper atmosphere, red auroras tend to be weaker compared to green auroras. However, since the auroral zone extends hundreds of kilometers or even farther north of China, the auroras visible in northern China have lower altitude angles, combined with the curvature of the Earth's surface and terrain obstruction. As a result, in regions like northern China with mid-latitudes, higher-altitude and relatively weaker red auroras are more easily observed.
Additionally, blue auroras result from the emission of light by nitrogen atoms after excitation/ionization, but nitrogen atoms are less prone to excitation and ionization, and thus, blue auroras are less frequent compared to red or green auroras.
Image source: National Geographic China
Geomagnetic storms originate from streams of high-energy charged particles that come from the sun, primarily from its outermost atmospheric layer – the corona. The corona is extremely hot and its matter is very sparse, existing in the form of charged plasma. Normally, these charged particles are confined by the sun’s magnetic field and have difficulty escaping en masse. However, there are two scenarios in which they can be ejected:
First, coronal holes – specific structures that are relatively stable (lasting several days), cooler in temperature, and have more open magnetic field lines – allow these charged particles to escape the confinement of the sun's magnetic field, creating high-speed streams from the coronal holes.
More intense than these are the violent solar activities (including but not limited to solar flares) that cause abnormal magnetic field disturbances, leading to local openings in the magnetic field lines. These “gaps” in the magnetic field more easily facilitate the rapid ejection of charged particle streams, resulting in coronal mass ejections (CMEs) – which often trigger more significant geomagnetic storms.
During the geomagnetic storm in December last year, an image of the Sun's far ultraviolet wavelength band was captured. The dark area in the lower right part of the image is a coronal hole, characterized by lower temperatures and more open magnetic field lines. It contributes to the generation of high-energy charged particle streams and recent geomagnetic storms and auroral activities. Image source: Solar Dynamics Observatory (SDO) under NASA.
When the high-energy particle stream associated with a coronal mass ejection (CME) enters the Earth's magnetic field, it compresses and deforms the geomagnetic field, injecting a large number of charged particles into the magnetospheric region, causing rapid changes in magnetospheric ring currents. As the changing currents generate changing magnetic fields, this part of the charged particle stream adds an additional induced magnetic field to the geomagnetic field, known as geomagnetic disturbance. The stronger disturbances are termed geomagnetic storms.
Geomagnetic storms and auroras are two sides of the effects of these high-energy solar particle streams and can be forecasted by monitoring the intensity of geomagnetic storm events.
Generally, CMEs that are more Earth-facing and faster in speed produce more intense geomagnetic storms. CMEs also come in different forms, typically measured by the angle between the two ends of the CME. Those that are completely circular (360°), known as halo CMEs, are usually Earth-directed and very fast, often causing strong geomagnetic storm events.
The interweaving of electromagnetic radiation: Effects of geomagnetic storms on life
Geomagnetic storms not only reflect drastic disturbances in the geomagnetic field but also represent impacts of high-energy particle streams on the Earth's upper atmosphere.
During such geomagnetic storm events, rapid changes in the magnetic field near the magnetic poles further induce eddy currents, causing certain disturbances to local power grids and other systems. Additionally, navigation systems like geomagnetic navigation, satellite navigation, and low-frequency radio wave navigation in high-latitude areas also experience significant disruptions.
With the enhancement of high-energy charged particle streams, some of these particles penetrate into the polar ionosphere, intensifying ionizing radiation at these altitudes, which may slightly affect flights passing through polar regions.
According to aggregated research data, the dose encountered during a single polar flight is 2.5-4 μSv/h (peaking during solar activity peaks), which, although 12-20 times the natural background radiation (about 0.2 μSv/h), remains well below the safety threshold for ionizing radiation dosage (recommended as 1000 μSv per year for the general public and 20000 μSv per year for occupational workers). However, for crew members working on polar routes year-round, some studies suggest that the total radiation dosage may approach the safety threshold, requiring further research for confirmation.
Beyond the atmosphere, high-energy particle streams and geomagnetic disturbances also affect the operation of electrical components and flight attitudes of space stations and satellites, necessitating caution for astronauts in orbit. Moreover, for some low-orbit spacecraft, the increased atmospheric density during geomagnetic storms may result in further atmospheric drag and increased resistance, affecting orbit adjustments or even premature deorbiting, requiring precautionary measures.
Regarding events of the magnitude of this recent geomagnetic storm, daily life in mid-latitude regions, including China, is unlikely to be significantly impacted, including electronic devices, communications, and flight operations.
For the general public, there is currently insufficient evidence to suggest that geomagnetic storms have an impact on physical health.
The most direct experience for ordinary people during stronger geomagnetic storms is the increased likelihood of witnessing vibrant auroras in high-latitude regions (specifically, areas with higher magnetic latitudes around the magnetic poles). As the high-energy particle streams expand toward the equator, auroras can also be observed in many mid-latitude regions, including northern China. However, as mentioned earlier, the auroral view in northern China is relatively limited and dim, requiring sufficiently open areas away from urban light pollution. [6] Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O., & Morschhauser, A. (2021). The Geomagnetic Kp Index and Derived Indices of Geomagnetic Activity. Space Weather, 19. https://doi.org/10.1029/2020SW002641.
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