Morphologies of omega band auroras
Abstract We examined the morphological signatures of 315 omega band aurora events observed using the Time History of Events and Macroscale Interactions during Substorm ground-based all-sky imager network over a period of 8 years. We find that omega bands can be classified into the following three su...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2017-08-01
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| Series: | Earth, Planets and Space |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s40623-017-0688-1 |
| _version_ | 1819064810317283328 |
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| author | Natsuo Sato Akira Sessai Yukimatu Yoshimasa Tanaka Tomoaki Hori |
| author_facet | Natsuo Sato Akira Sessai Yukimatu Yoshimasa Tanaka Tomoaki Hori |
| author_sort | Natsuo Sato |
| collection | DOAJ |
| description | Abstract We examined the morphological signatures of 315 omega band aurora events observed using the Time History of Events and Macroscale Interactions during Substorm ground-based all-sky imager network over a period of 8 years. We find that omega bands can be classified into the following three subtypes: (1) classical (O-type) omega bands, (2) torch or tongue (T-type) omega bands, and (3) combinations of classical and torch or tongue (O/T-type) omega bands. The statistical results show that T-type bands occur the most frequently (45%), followed by O/T-type bands (35%) and O-type bands (18%). We also examined the morphologies of the omega bands during their formation, from the growth period to the declining period through the maximum period. Interestingly, the omega bands are not stable, but rather exhibit dynamic changes in shape, intensity, and motion. They grow from small-scale bumps (seeds) at the poleward boundary of preexisting east–west-aligned auroras, rather than via the rotation or shear motion of preexisting east–west-aligned auroras, and do not exhibit any shear motion during the periods of auroral activity growth. Furthermore, the auroral luminosity is observed to increase during the declining period, and the total time from the start of the growth period to the end of the declining period is found to be about 20 min. Such dynamical signatures may be important in determining the mechanism responsible for omega band formation. |
| first_indexed | 2024-12-21T15:36:29Z |
| format | Article |
| id | doaj.art-621c2b95d26f44f18feb33319a7c96f4 |
| institution | Directory Open Access Journal |
| issn | 1880-5981 |
| language | English |
| last_indexed | 2024-12-21T15:36:29Z |
| publishDate | 2017-08-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Earth, Planets and Space |
| spelling | doaj.art-621c2b95d26f44f18feb33319a7c96f42022-12-21T18:58:37ZengSpringerOpenEarth, Planets and Space1880-59812017-08-0169111110.1186/s40623-017-0688-1Morphologies of omega band aurorasNatsuo Sato0Akira Sessai Yukimatu1Yoshimasa Tanaka2Tomoaki Hori3National Institute of Polar ResearchNational Institute of Polar ResearchNational Institute of Polar ResearchInstitute for Space-Earth Environmental Research, Nagoya UniversityAbstract We examined the morphological signatures of 315 omega band aurora events observed using the Time History of Events and Macroscale Interactions during Substorm ground-based all-sky imager network over a period of 8 years. We find that omega bands can be classified into the following three subtypes: (1) classical (O-type) omega bands, (2) torch or tongue (T-type) omega bands, and (3) combinations of classical and torch or tongue (O/T-type) omega bands. The statistical results show that T-type bands occur the most frequently (45%), followed by O/T-type bands (35%) and O-type bands (18%). We also examined the morphologies of the omega bands during their formation, from the growth period to the declining period through the maximum period. Interestingly, the omega bands are not stable, but rather exhibit dynamic changes in shape, intensity, and motion. They grow from small-scale bumps (seeds) at the poleward boundary of preexisting east–west-aligned auroras, rather than via the rotation or shear motion of preexisting east–west-aligned auroras, and do not exhibit any shear motion during the periods of auroral activity growth. Furthermore, the auroral luminosity is observed to increase during the declining period, and the total time from the start of the growth period to the end of the declining period is found to be about 20 min. Such dynamical signatures may be important in determining the mechanism responsible for omega band formation.http://link.springer.com/article/10.1186/s40623-017-0688-1Omega band auroraTorch auroraTongue auroraPulsating auroraAll-sky imagerTHEMIS |
| spellingShingle | Natsuo Sato Akira Sessai Yukimatu Yoshimasa Tanaka Tomoaki Hori Morphologies of omega band auroras Earth, Planets and Space Omega band aurora Torch aurora Tongue aurora Pulsating aurora All-sky imager THEMIS |
| title | Morphologies of omega band auroras |
| title_full | Morphologies of omega band auroras |
| title_fullStr | Morphologies of omega band auroras |
| title_full_unstemmed | Morphologies of omega band auroras |
| title_short | Morphologies of omega band auroras |
| title_sort | morphologies of omega band auroras |
| topic | Omega band aurora Torch aurora Tongue aurora Pulsating aurora All-sky imager THEMIS |
| url | http://link.springer.com/article/10.1186/s40623-017-0688-1 |
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