Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone
Seasonal variation in the latitude of geomagnetically conjugate point was obtained statistically using the imaging riometers at Syowa-Tjornes conjugate pair stations. The conjugate point was evaluated experimentally from the relative location of band-type CNA (Cosmic Noise Absorption) appearing at t...
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National Institute of Polar Research
1998
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Online Access: | https://doi.org/10.15094/00009026 https://doaj.org/article/6f9ff90c2c7c4c71ac109ac44ada4224 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:6f9ff90c2c7c4c71ac109ac44ada4224 2023-05-15T16:50:47+02:00 Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone Yuiti Fujita Hisao Yamagishi Natsuo Sato 1998-03-01 https://doi.org/10.15094/00009026 https://doaj.org/article/6f9ff90c2c7c4c71ac109ac44ada4224 en other eng National Institute of Polar Research doi:10.15094/00009026 0085-7289 2432-079X https://doaj.org/article/6f9ff90c2c7c4c71ac109ac44ada4224 undefined Antarctic Record, Vol 42, Iss 1, Pp 1-19 (1998) geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 1998 fttriple https://doi.org/10.15094/00009026 2023-01-22T19:30:59Z Seasonal variation in the latitude of geomagnetically conjugate point was obtained statistically using the imaging riometers at Syowa-Tjornes conjugate pair stations. The conjugate point was evaluated experimentally from the relative location of band-type CNA (Cosmic Noise Absorption) appearing at the conjugate stations, associated with auroral breakups in premidnight hours. The statistical analyses were made for poleward moving CNA-bands observed during February 1992 to December 1993. Following characteristics are obtained. (1) The poleward expanding speed of the CNA-bands differs significantly between the two hemispheres : it is faster at Syowa than Tjornes in Iceland by 15% on average. This difference may be attributable to an interhemispherical asymmetry of the magnetic flux tube radii mapped to the ionospheres, which is caused by the differences in the geomagnetic field strength and dip angles between the both stations. (2) The conjugate point of Syowa mapped to the northern hemisphere moves most equatorward in June and most poleward in December from Tjornes. The latitudinal range of the seasonal displacement is about 200km for the average geomagnetic activities of Kp=4. (3) The seasonal displacement agrees well with the calculations of the conjugate points using the combination of IGRF 1995 and Tsyganenko 1989 geomagnetic field models. Article in Journal/Newspaper Iceland Unknown |
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geo Yuiti Fujita Hisao Yamagishi Natsuo Sato Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
topic_facet |
geo |
description |
Seasonal variation in the latitude of geomagnetically conjugate point was obtained statistically using the imaging riometers at Syowa-Tjornes conjugate pair stations. The conjugate point was evaluated experimentally from the relative location of band-type CNA (Cosmic Noise Absorption) appearing at the conjugate stations, associated with auroral breakups in premidnight hours. The statistical analyses were made for poleward moving CNA-bands observed during February 1992 to December 1993. Following characteristics are obtained. (1) The poleward expanding speed of the CNA-bands differs significantly between the two hemispheres : it is faster at Syowa than Tjornes in Iceland by 15% on average. This difference may be attributable to an interhemispherical asymmetry of the magnetic flux tube radii mapped to the ionospheres, which is caused by the differences in the geomagnetic field strength and dip angles between the both stations. (2) The conjugate point of Syowa mapped to the northern hemisphere moves most equatorward in June and most poleward in December from Tjornes. The latitudinal range of the seasonal displacement is about 200km for the average geomagnetic activities of Kp=4. (3) The seasonal displacement agrees well with the calculations of the conjugate points using the combination of IGRF 1995 and Tsyganenko 1989 geomagnetic field models. |
format |
Article in Journal/Newspaper |
author |
Yuiti Fujita Hisao Yamagishi Natsuo Sato |
author_facet |
Yuiti Fujita Hisao Yamagishi Natsuo Sato |
author_sort |
Yuiti Fujita |
title |
Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
title_short |
Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
title_full |
Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
title_fullStr |
Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
title_full_unstemmed |
Seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
title_sort |
seasonal variation in the latitude of geomagnetically conjugate points observed with imaging riometers in the auroral zone |
publisher |
National Institute of Polar Research |
publishDate |
1998 |
url |
https://doi.org/10.15094/00009026 https://doaj.org/article/6f9ff90c2c7c4c71ac109ac44ada4224 |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Antarctic Record, Vol 42, Iss 1, Pp 1-19 (1998) |
op_relation |
doi:10.15094/00009026 0085-7289 2432-079X https://doaj.org/article/6f9ff90c2c7c4c71ac109ac44ada4224 |
op_rights |
undefined |
op_doi |
https://doi.org/10.15094/00009026 |
_version_ |
1766040901709201408 |