Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity
International audience In a previous study it was reported that whistler- mode signals received at Faraday, Antarctica (65 ° S,64 ° W) and Dunedin, New Zealand (46 ° S,171 ° E) with entry regions in Pacific longitudes (typically from the VLF transmitter NLK, Seattle, USA) showed an increase in trans...
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ftccsdartic:oai:HAL:hal-00316302v1 2023-11-12T04:05:49+01:00 Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity Thomson, N. R. Clilverd, M. A. Smith, A. J. Department of Physics Dunedin University of Otago Dunedin, Nouvelle-Zélande British Antarctic Survey (BAS) Natural Environment Research Council (NERC) 1997 https://hal.science/hal-00316302 https://hal.science/hal-00316302/document https://hal.science/hal-00316302/file/angeo-15-999-1997.pdf en eng HAL CCSD European Geosciences Union hal-00316302 https://hal.science/hal-00316302 https://hal.science/hal-00316302/document https://hal.science/hal-00316302/file/angeo-15-999-1997.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00316302 Annales Geophysicae, 1997, 15 (8), pp.999-1004 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 1997 ftccsdartic 2023-10-21T23:08:39Z International audience In a previous study it was reported that whistler- mode signals received at Faraday, Antarctica (65 ° S,64 ° W) and Dunedin, New Zealand (46 ° S,171 ° E) with entry regions in Pacific longitudes (typically from the VLF transmitter NLK, Seattle, USA) showed an increase in transmission of wave energy as magnetic activity increased. However, signals with entry regions in Atlantic longitudes (typically from the NSS transmitter, Annapolis, USA) did not appear to show such a relationship. This paper reports the results of a study of the same two longitude ranges but with the opposite transmitter providing additional whistler-mode signal information, with L -values in the range 1.8?2.6. Transmissions from NLK once again indicate a relationship between the transmission of wave energy and magnetic activity even though the signals were propagating in Atlantic longitudes, not Pacific. Any trend in NSS events observed at Dunedin was obscured by a limited range of magnetic activity, and duct exit regions so close to the receiver that small-scale excitation effects appeared to be occurring. However, by combining data from both longitudes, i.e Pacific and Atlantic, and using only ducts with exit regions that were >500km from the receiver, NSS events were found to show the same trend as NLK events. No significant longitude-dependent or transmitter-dependent variations in duct efficiency could be detected. Duct efficiency increases by a factor of about 30 with K p =2?8 and this result is discussed in terms of changes in wave-particle interactions and duct size. Article in Journal/Newspaper Antarc* Antarctica Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Pacific New Zealand Faraday ENVELOPE(-64.256,-64.256,-65.246,-65.246) |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Thomson, N. R. Clilverd, M. A. Smith, A. J. Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience In a previous study it was reported that whistler- mode signals received at Faraday, Antarctica (65 ° S,64 ° W) and Dunedin, New Zealand (46 ° S,171 ° E) with entry regions in Pacific longitudes (typically from the VLF transmitter NLK, Seattle, USA) showed an increase in transmission of wave energy as magnetic activity increased. However, signals with entry regions in Atlantic longitudes (typically from the NSS transmitter, Annapolis, USA) did not appear to show such a relationship. This paper reports the results of a study of the same two longitude ranges but with the opposite transmitter providing additional whistler-mode signal information, with L -values in the range 1.8?2.6. Transmissions from NLK once again indicate a relationship between the transmission of wave energy and magnetic activity even though the signals were propagating in Atlantic longitudes, not Pacific. Any trend in NSS events observed at Dunedin was obscured by a limited range of magnetic activity, and duct exit regions so close to the receiver that small-scale excitation effects appeared to be occurring. However, by combining data from both longitudes, i.e Pacific and Atlantic, and using only ducts with exit regions that were >500km from the receiver, NSS events were found to show the same trend as NLK events. No significant longitude-dependent or transmitter-dependent variations in duct efficiency could be detected. Duct efficiency increases by a factor of about 30 with K p =2?8 and this result is discussed in terms of changes in wave-particle interactions and duct size. |
author2 |
Department of Physics Dunedin University of Otago Dunedin, Nouvelle-Zélande British Antarctic Survey (BAS) Natural Environment Research Council (NERC) |
format |
Article in Journal/Newspaper |
author |
Thomson, N. R. Clilverd, M. A. Smith, A. J. |
author_facet |
Thomson, N. R. Clilverd, M. A. Smith, A. J. |
author_sort |
Thomson, N. R. |
title |
Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
title_short |
Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
title_full |
Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
title_fullStr |
Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
title_full_unstemmed |
Evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
title_sort |
evidence of more efficient whistler-mode transmission during periods of increased magnetic activity |
publisher |
HAL CCSD |
publishDate |
1997 |
url |
https://hal.science/hal-00316302 https://hal.science/hal-00316302/document https://hal.science/hal-00316302/file/angeo-15-999-1997.pdf |
long_lat |
ENVELOPE(-64.256,-64.256,-65.246,-65.246) |
geographic |
Pacific New Zealand Faraday |
geographic_facet |
Pacific New Zealand Faraday |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00316302 Annales Geophysicae, 1997, 15 (8), pp.999-1004 |
op_relation |
hal-00316302 https://hal.science/hal-00316302 https://hal.science/hal-00316302/document https://hal.science/hal-00316302/file/angeo-15-999-1997.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782342102823206912 |