EISCAT observations of plasma patches at sub-auroral cusp latitudes
International audience 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 combinat...
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ftinsu:oai:HAL:hal-00318165v1 2023-11-12T04:16:36+01:00 EISCAT observations of plasma patches at sub-auroral cusp latitudes Moen, J. Carlson, H. C. Oksavik, K. Nielsen, C. P. Pryse, S. E. Middleton, H. R. Mccrea, I. W. Gallop, P. Department of Physics Okayama University Air Force Research Laboratory (AFRL) United States Air Force (USAF) Johns Hopkins University Applied Physics Laboratory Laurel, MD (APL) Norwegian Polar Institute Institute of Mathematical and Physical Sciences University of Wales STFC Rutherford Appleton Laboratory (RAL) Science and Technology Facilities Council (STFC) 2006-09-20 https://hal.science/hal-00318165 https://hal.science/hal-00318165/document https://hal.science/hal-00318165/file/angeo-24-2363-2006.pdf en eng HAL CCSD European Geosciences Union hal-00318165 https://hal.science/hal-00318165 https://hal.science/hal-00318165/document https://hal.science/hal-00318165/file/angeo-24-2363-2006.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00318165 Annales Geophysicae, 2006, 24 (9), pp.2363-2374 [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 2006 ftinsu 2023-10-25T16:25:04Z International audience 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 Institut national des sciences de l'Univers: HAL-INSU Birkeland ENVELOPE(16.587,16.587,68.594,68.594) Svalbard |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
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 Moen, J. Carlson, H. C. Oksavik, K. Nielsen, C. P. Pryse, S. E. Middleton, H. R. Mccrea, I. W. Gallop, P. EISCAT observations of plasma patches at sub-auroral cusp latitudes |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience 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. |
author2 |
Department of Physics Okayama University Air Force Research Laboratory (AFRL) United States Air Force (USAF) Johns Hopkins University Applied Physics Laboratory Laurel, MD (APL) Norwegian Polar Institute Institute of Mathematical and Physical Sciences University of Wales STFC Rutherford Appleton Laboratory (RAL) Science and Technology Facilities Council (STFC) |
format |
Article in Journal/Newspaper |
author |
Moen, J. Carlson, H. C. Oksavik, K. Nielsen, C. P. Pryse, S. E. Middleton, H. R. Mccrea, I. W. Gallop, P. |
author_facet |
Moen, J. Carlson, H. C. Oksavik, K. Nielsen, C. P. Pryse, S. E. Middleton, H. R. Mccrea, I. W. Gallop, P. |
author_sort |
Moen, J. |
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 |
HAL CCSD |
publishDate |
2006 |
url |
https://hal.science/hal-00318165 https://hal.science/hal-00318165/document https://hal.science/hal-00318165/file/angeo-24-2363-2006.pdf |
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 |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00318165 Annales Geophysicae, 2006, 24 (9), pp.2363-2374 |
op_relation |
hal-00318165 https://hal.science/hal-00318165 https://hal.science/hal-00318165/document https://hal.science/hal-00318165/file/angeo-24-2363-2006.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782333661007314944 |