Auroras, also known as Northern or Southern lights depending on whether they occur near the North or South Pole, are natural displays of light in the Earth's sky. Typically these lights are dimly present at night. However, sometimes these otherwise faint features explode in brightness and can even break up into separate glowing hallmarks, appearing as spectacular bursts of luminous manifestations. This striking and picturesque phenomenon is known as an auroral breakup.
Now, Japanese scientists have quantitatively confirmed how energetic this phenomenon can be. Using a combination of cutting-edge ground-based technology and new space-borne observations, they have demonstrated the essential role of an auroral breakup in ionizing the deep atmosphere. The research furthers our understanding of one of the most visually stunning natural phenomena.
The findings were published in Earth, Planets and Space on January 23, 2019.
The sun fires beams of charged particles, or plasma, toward Earth. Also referred to as solar winds, this plasma is mostly made up of electrons, protons and alpha particles. When these particles interact with the Earth's magnetic field, electrical currents are carried by electrons into the Earth's atmosphere. This reaction between the electrons and their atmospheric constituents emits light of varying color and complexity, visible as an aurora. However, little is known about how energetic the electrons can be when these lights explode into the stunning lightshows known as auroral breakups. So far, the assumption has been that electrons of a specific energy level are responsible for this rare phenomenon.
In the new study, the scientists report that, contrary to conventional thinking, a specific kind of electrons with much higher energy, called radiation belt electrons, are involved in the auroral breakup. Named after their location in the Earth's radiation belt, radiation belt electrons had not been clearly associated with auroral breakups before. The research team based their conclusions on a dataset collected via advanced technology and simulations.
"Radiation belt electrons are released from the Earth's magnetic field and charge the mesosphere during auroral breakup. This fact was quantitatively confirmed by both cutting-edge ground-based and new space-borne observations," adds Ryuho Kataoka, Ph.D., associate professor at the National Institute of Polar Research and the corresponding author. "This study also provides a good example how Arase satellite and PANSY radar can collaborate to understand the connection between space and atmosphere."
In their future research endeavors, the Professor Kataoka and his team hope to understand how the radiation belt electrons are released during the short-lasting period of auroral breakup. "The ultimate goal is to understand the interplay between auroras and radiation belts," Professor Kataoka adds.
This research was supported by several Japan Society for the Promotion of Science-Kakenhi grants.
About National Institute of Polar Research (NIPR)
The NIPR engages in comprehensive research via observation stations in Arctic and Antarctica. As a member of the Research Organization of Information and Systems (ROIS), the NIPR provides researchers throughout Japan with infrastructure support for Arctic and Antarctic observations, plans and implements Japan's Antarctic observation projects, and conducts Arctic researches of various scientific fields such as the atmosphere, ice sheets, the ecosystem, the upper atmosphere, the aurora and the Earth's magnetic field. In addition to the research projects, the NIPR also organizes the Japanese Antarctic Research Expedition and manages samples and data obtained during such expeditions and projects. As a core institution in researches of the polar regions, the NIPR also offers graduate students with a global perspective on originality through its doctoral program. For more information about the NIPR, please visit: https:/
About the Research Organization of Information and Systems (ROIS)
The Research Organization of Information and Systems (ROIS) is a parent organization of four national institutes (National Institute of Polar Research, National Institute of Informatics, the Institute of Statistical Mathematics and National Institute of Genetics) and the Joint Support-Center for Data Science Research. It is our mission to promote integrated, cutting-edge research that goes beyond the barriers of these institutions, in addition to facilitating their research activities, as members of inter-university research institutes.
The coordination of these institutions, facilitated by ROIS, will contribute to opening new areas of research and performing integrated transdisciplinary research. This framework will allow a holistic approach to the complex issues of life, earth, environmental and social sciences, including the generation of large scale and heterogeneous data from observations, measurements and experiments, knowledge extraction from these data, discovery of scientific truths, technological advancements in database construction and implementation. ROIS will also widely share with the community, the outcomes, resources and research platforms necessary for new frontiers of research.
Informatics methodologies utilized to elucidate complex systems, research and development related to advanced usage of databases and networks, in addition to operation of databases and networks will also enable ROIS to serve as an information platform that will support rapid and effective development of research both in Japan and abroad.