EISCAT observations of plasma patches at sub-auroral cusp latitudes
A sequence of 3 patches of high-density (10 12 m −3 ) cold plasma on a horizontal scale-size of 300–700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sk...
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ftdoajarticles:oai:doaj.org/article:995981b866a241bcadd06fb9e2091fbc 2023-05-15T16:04:35+02:00 EISCAT observations of plasma patches at sub-auroral cusp latitudes J. Moen H. C. Carlson K. Oksavik C. P. Nielsen S. E. Pryse H. R. Middleton I. W. McCrea P. Gallop 2006-09-01T00:00:00Z https://doi.org/10.5194/angeo-24-2363-2006 https://doaj.org/article/995981b866a241bcadd06fb9e2091fbc EN eng Copernicus Publications https://www.ann-geophys.net/24/2363/2006/angeo-24-2363-2006.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-24-2363-2006 0992-7689 1432-0576 https://doaj.org/article/995981b866a241bcadd06fb9e2091fbc Annales Geophysicae, Vol 24, Pp 2363-2374 (2006) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2006 ftdoajarticles https://doi.org/10.5194/angeo-24-2363-2006 2022-12-31T01:07:32Z A sequence of 3 patches of high-density (10 12 m −3 ) cold plasma on a horizontal scale-size of 300–700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sky observations demonstrates that the patches must have been segmented equatorward of the cusp/cleft auroral display, and hence their properties had not yet been influenced by cusp particle showers and electrodynamics on open flux tubes. The last patch in the sequence was intersected by radio tomography observations, and was found to be located adjacent to a broader region of the same high electron density further south. The patches occurred under moderately active conditions (Kp=3) and the total electron content (TEC) of the high-density plasma was 45 TEC units. The train of patches appeared as a segmentation of the tongue of ionization. The sequence of patches occurred in association with a sequence of flow bursts in the dusk cell return flow. It is proposed that reconnection driven pulsed convection is able to create sub-auroral patches in the region where high density mid-latitude plasma is diverted poleward toward the cusp. It is the downward Birkeland current sheet located at the equatorward boundary of the flow disturbance that represents the actual cutting mechanism. Article in Journal/Newspaper EISCAT Svalbard Directory of Open Access Journals: DOAJ Articles Birkeland ENVELOPE(16.587,16.587,68.594,68.594) Svalbard Annales Geophysicae 24 9 2363 2374 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 J. Moen H. C. Carlson K. Oksavik C. P. Nielsen S. E. Pryse H. R. Middleton I. W. McCrea P. Gallop EISCAT observations of plasma patches at sub-auroral cusp latitudes |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
A sequence of 3 patches of high-density (10 12 m −3 ) cold plasma on a horizontal scale-size of 300–700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sky observations demonstrates that the patches must have been segmented equatorward of the cusp/cleft auroral display, and hence their properties had not yet been influenced by cusp particle showers and electrodynamics on open flux tubes. The last patch in the sequence was intersected by radio tomography observations, and was found to be located adjacent to a broader region of the same high electron density further south. The patches occurred under moderately active conditions (Kp=3) and the total electron content (TEC) of the high-density plasma was 45 TEC units. The train of patches appeared as a segmentation of the tongue of ionization. The sequence of patches occurred in association with a sequence of flow bursts in the dusk cell return flow. It is proposed that reconnection driven pulsed convection is able to create sub-auroral patches in the region where high density mid-latitude plasma is diverted poleward toward the cusp. It is the downward Birkeland current sheet located at the equatorward boundary of the flow disturbance that represents the actual cutting mechanism. |
format |
Article in Journal/Newspaper |
author |
J. Moen H. C. Carlson K. Oksavik C. P. Nielsen S. E. Pryse H. R. Middleton I. W. McCrea P. Gallop |
author_facet |
J. Moen H. C. Carlson K. Oksavik C. P. Nielsen S. E. Pryse H. R. Middleton I. W. McCrea P. Gallop |
author_sort |
J. Moen |
title |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
title_short |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
title_full |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
title_fullStr |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
title_full_unstemmed |
EISCAT observations of plasma patches at sub-auroral cusp latitudes |
title_sort |
eiscat observations of plasma patches at sub-auroral cusp latitudes |
publisher |
Copernicus Publications |
publishDate |
2006 |
url |
https://doi.org/10.5194/angeo-24-2363-2006 https://doaj.org/article/995981b866a241bcadd06fb9e2091fbc |
long_lat |
ENVELOPE(16.587,16.587,68.594,68.594) |
geographic |
Birkeland Svalbard |
geographic_facet |
Birkeland Svalbard |
genre |
EISCAT Svalbard |
genre_facet |
EISCAT Svalbard |
op_source |
Annales Geophysicae, Vol 24, Pp 2363-2374 (2006) |
op_relation |
https://www.ann-geophys.net/24/2363/2006/angeo-24-2363-2006.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-24-2363-2006 0992-7689 1432-0576 https://doaj.org/article/995981b866a241bcadd06fb9e2091fbc |
op_doi |
https://doi.org/10.5194/angeo-24-2363-2006 |
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Annales Geophysicae |
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24 |
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9 |
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2363 |
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2374 |
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