May 21, 2024

Revealing the Role of Earth’s Upper Atmosphere in the Formation of Geomagnetic Storms

New research led by scientists from Nagoya University in Japan and the University of New Hampshire in the United States highlights the crucial role played by Earth’s upper atmosphere in the development of large geomagnetic storms. This study sheds light on the previously underestimated significance of the Earth’s atmosphere in determining the characteristics of these storms. Geomagnetic storms can have profound effects on the Earth’s magnetic field, leading to unwanted currents in power grids and disruptions in radio signals and GPS systems. The findings of this research may aid in the prediction of these storms and their potential consequences.

Scientists have long been aware of the connection between geomagnetic storms and solar activities. The Sun’s outer layer is composed of hot charged particles, which form the “solar wind” that flows out into space and interacts with celestial bodies like the Earth. When these particles reach the Earth’s magnetic field, known as the magnetosphere, they interact with it, creating what is known as space weather. Space weather refers to the conditions in space that can impact the Earth and technological systems such as satellites.

One crucial component of the magnetosphere is the magnetotail, which extends away from the Sun in the direction of the solar wind flow. Within the magnetotail lies the plasma sheet region, rich in charged particles called plasma. The plasma sheet serves as the source region for the particles that enter the inner magnetosphere and give rise to the current responsible for geomagnetic storms.

While the importance of the Sun’s role in this process is widely recognized, an international team of researchers sought to unravel the mystery surrounding the contribution of Earth’s plasma to the magnetosphere and how it changes during a geomagnetic storm. Lynn Kistler, Designated Professor at Nagoya University and Professor at the University of New Hampshire, Yoshizumi Miyoshi, Professor at Nagoya University, and Tomoaki Hori, Designated Professor at Nagoya University, led this group of researchers.

In their study, the researchers analyzed data from a major geomagnetic storm that occurred on September 7-8, 2017. During this event, a massive coronal mass ejection from the Sun collided with Earth’s atmosphere, resulting in a significant geomagnetic storm. This impact disrupted the magnetosphere and led to interference with radio signals, GPS systems, and precision timing applications.

To investigate the ion transport during this event, the researchers retrospectively analyzed data from various space missions, including the NASA/Magnetospheric Multiscale (MMS) mission, the Japanese Arase mission, the ESA/Cluster mission, and the NASA/Wind mission. By distinguishing ions from the solar wind and those from the ionosphere, they were able to track changes in the source composition.

The researchers observed substantial variations in the composition and other properties of the near-Earth plasma sheet as the storm progressed. These properties, such as density, particle energy distribution, and composition, play a crucial role in the development of geomagnetic storms. Interestingly, the researchers discovered that at the initiation of the storm, the plasma from the ionosphere became the dominant source, replacing the previously dominant solar wind.

The most significant finding was the transition from predominantly solar-dominated plasma to ionosphere-dominated plasma at the beginning of the geomagnetic storm. According to Kistler, this indicates that the geomagnetic storm results in increased outflow from Earth’s ionosphere, with the ionospheric plasma rapidly spreading throughout the magnetosphere.

In summary, this research enhances our understanding of the formation of geomagnetic storms by emphasizing the importance of Earth’s ionospheric plasma. The study provides compelling evidence that not only solar plasma but also plasma from Earth contributes to the occurrence of geomagnetic storms. The properties of the plasma sheet, including density, particle energy distribution, and composition, vary depending on the source and significantly impact the development of these storms.

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1. Source: Coherent Market Insights, Public sources, Desk research
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