New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5
We reveal previously unknown quasi-periodic (QP) very low frequency (VLF) emissions at the unusually high-frequency band of ∼ 7–12 kHz by applying the digital filtering of strong atmospherics to the ground-based VLF data recorded at Kannuslehto station (KAN). It is located in northern Finland at L ∼...
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2018
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00005455 2023-05-15T17:42:36+02:00 New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 Manninen, Jyrki Kleimenova, Natalia Turunen, Tauno Gromova, Liudmila 2018-06 electronic https://doi.org/10.5194/angeo-36-915-2018 https://noa.gwlb.de/receive/cop_mods_00005455 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005412/angeo-36-915-2018.pdf https://angeo.copernicus.org/articles/36/915/2018/angeo-36-915-2018.pdf eng eng Copernicus Publications Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-36-915-2018 https://noa.gwlb.de/receive/cop_mods_00005455 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005412/angeo-36-915-2018.pdf https://angeo.copernicus.org/articles/36/915/2018/angeo-36-915-2018.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2018 ftnonlinearchiv https://doi.org/10.5194/angeo-36-915-2018 2022-02-08T22:59:33Z We reveal previously unknown quasi-periodic (QP) very low frequency (VLF) emissions at the unusually high-frequency band of ∼ 7–12 kHz by applying the digital filtering of strong atmospherics to the ground-based VLF data recorded at Kannuslehto station (KAN). It is located in northern Finland at L ∼ 5.5. The frequencies of QP emissions are much higher than the equatorial electron gyrofrequency at L ∼ 5.5. Thus, these emissions must have been generated at much lower L shells than KAN. Two high-frequency QP emission events have been studied in detail. The emissions were right-hand polarized waves indicating an overhead location of the exit area of waves in the ionosphere. In one event, the spectral–temporal forms of the emissions looked like a series of giant “bullets” due to the very abrupt cessation. Unfortunately, we could not explain such a strange dynamic spectral shape of the waves. In the second event, the modulation period was about 3 min under the absence of simultaneous geomagnetic pulsations. The studied emissions lasted about 4 h and were observed under the very quiet geomagnetic activity. The adequate mechanisms of the generation and propagation of the revealed high-frequency QP emissions have not yet been established. We speculate that studied QP emissions can be attributed to the auto-oscillations of the cyclotron instability in the magnetospheric plasma maser. Article in Journal/Newspaper Northern Finland Niedersächsisches Online-Archiv NOA Annales Geophysicae 36 3 915 923 |
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English |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Manninen, Jyrki Kleimenova, Natalia Turunen, Tauno Gromova, Liudmila New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
topic_facet |
article Verlagsveröffentlichung |
description |
We reveal previously unknown quasi-periodic (QP) very low frequency (VLF) emissions at the unusually high-frequency band of ∼ 7–12 kHz by applying the digital filtering of strong atmospherics to the ground-based VLF data recorded at Kannuslehto station (KAN). It is located in northern Finland at L ∼ 5.5. The frequencies of QP emissions are much higher than the equatorial electron gyrofrequency at L ∼ 5.5. Thus, these emissions must have been generated at much lower L shells than KAN. Two high-frequency QP emission events have been studied in detail. The emissions were right-hand polarized waves indicating an overhead location of the exit area of waves in the ionosphere. In one event, the spectral–temporal forms of the emissions looked like a series of giant “bullets” due to the very abrupt cessation. Unfortunately, we could not explain such a strange dynamic spectral shape of the waves. In the second event, the modulation period was about 3 min under the absence of simultaneous geomagnetic pulsations. The studied emissions lasted about 4 h and were observed under the very quiet geomagnetic activity. The adequate mechanisms of the generation and propagation of the revealed high-frequency QP emissions have not yet been established. We speculate that studied QP emissions can be attributed to the auto-oscillations of the cyclotron instability in the magnetospheric plasma maser. |
format |
Article in Journal/Newspaper |
author |
Manninen, Jyrki Kleimenova, Natalia Turunen, Tauno Gromova, Liudmila |
author_facet |
Manninen, Jyrki Kleimenova, Natalia Turunen, Tauno Gromova, Liudmila |
author_sort |
Manninen, Jyrki |
title |
New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
title_short |
New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
title_full |
New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
title_fullStr |
New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
title_full_unstemmed |
New high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ∼ 5.5 |
title_sort |
new high-frequency (7–12 khz) quasi-periodic vlf emissions observed on the ground at l ∼ 5.5 |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-36-915-2018 https://noa.gwlb.de/receive/cop_mods_00005455 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005412/angeo-36-915-2018.pdf https://angeo.copernicus.org/articles/36/915/2018/angeo-36-915-2018.pdf |
genre |
Northern Finland |
genre_facet |
Northern Finland |
op_relation |
Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-36-915-2018 https://noa.gwlb.de/receive/cop_mods_00005455 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00005412/angeo-36-915-2018.pdf https://angeo.copernicus.org/articles/36/915/2018/angeo-36-915-2018.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/angeo-36-915-2018 |
container_title |
Annales Geophysicae |
container_volume |
36 |
container_issue |
3 |
container_start_page |
915 |
op_container_end_page |
923 |
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1766144490766073856 |