In a groundbreaking study, researchers from Japan’s Nagoya University and the University of New Hampshire in the USA have discovered a key role played by Earth’s upper atmosphere in creating powerful geomagnetic storms.
Their study, recently published in the prestigious journal Nature Communications, highlights a crucial aspect that has been largely overlooked until now: the influence of the Earth’s atmosphere on these storms.
Geomagnetic storms are significant disturbances in Earth’s magnetic field that can wreak havoc on our modern technological systems, causing disruptions in power grids, GPS signals, and radio communications.
These storms are primarily driven by the activity of the sun, which emits a stream of charged particles known as the solar wind.
When these particles collide with the Earth’s magnetosphere—the protective magnetic bubble surrounding our planet—they can trigger these disruptive storms.
The team’s research focused on the part of the magnetosphere called the magnetotail, which stretches away from the sun.
Within the magnetotail lies the plasma sheet, a region brimming with plasma, which consists of charged particles.
This plasma sheet acts as a kind of reservoir for particles that eventually move into the inner magnetosphere, generating currents that contribute to the formation of geomagnetic storms.
While it’s well-established that the sun’s solar wind is a significant factor, the researchers were curious about the contribution of plasma originating from Earth itself, particularly during storm conditions.
Led by experts including Professors Lynn Kistler, Yoshizumi Miyoshi, and Tomoaki Hori, the team scrutinized a major geomagnetic storm that occurred between September 7 and 8, 2017. This storm was the result of an intense coronal mass ejection—a massive burst of solar material—from the sun that struck Earth’s atmosphere.
The collision caused significant disturbances, resulting in the type of storm that can interfere with various technologies that rely on precise timing and GPS signals.
The researchers analyzed ion transport—the movement of charged particles—during this event by pooling data from multiple space missions, such as NASA’s MMS mission, Japan’s Arase mission, the European Space Agency’s Cluster mission, and NASA’s Wind mission.
By differentiating between ions coming from the solar wind and those from Earth’s ionosphere, they could trace the origins of the plasma affecting the magnetosphere.
Their analysis led to an intriguing discovery: at the onset of the geomagnetic storm, the composition of the plasma shifted dramatically from being dominated by particles from the solar wind to being predominantly made up of particles from the ionosphere, the upper layer of Earth’s atmosphere.
Professor Kistler explained the significance of this finding, stating that the onset of the geomagnetic storm propels a surge of plasma from the ionosphere into the magnetosphere.
This ionospheric plasma doesn’t just linger around; it moves swiftly throughout the magnetosphere, playing a more active role in the storm’s development than previously thought.
The team’s research thus sheds light on how geomagnetic storms evolve by demonstrating how Earth’s own plasma contributes to these space weather events.
In essence, the characteristics of the plasma sheet, such as the density of particles, their energy, and their makeup, can influence the severity of geomagnetic storms. And these characteristics differ depending on the source of the plasma, whether it’s the solar wind or Earth’s ionosphere.
This new insight not only advances our understanding of geomagnetic storms but also has practical implications.
It could enhance our ability to predict which storms will have the most significant impact on Earth and our technological infrastructure, potentially allowing for better preparation and mitigation strategies to protect critical systems.
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Source: Nagoya University.
