Evidence for solar-production as a source of polar-cap plasma
The focus of the study is a region of enhanced ionospheric densities observed by the EISCAT Svalbard radar in the polar F-region near local magnetic noon under conditions of IMF B z <0. Multi-instrument observations, using optical, spacecraft and radar instrumentation, together with radio tomogra...
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ftcopernicus:oai:publications.copernicus.org:angeo35154 2023-05-15T16:04:33+02:00 Evidence for solar-production as a source of polar-cap plasma Pryse, S. E. Sims, R. W. Moen, J. Kersley, L. Lorentzen, D. Denig, W. F. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-22-1093-2004 https://angeo.copernicus.org/articles/22/1093/2004/ eng eng doi:10.5194/angeo-22-1093-2004 https://angeo.copernicus.org/articles/22/1093/2004/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-22-1093-2004 2020-07-20T16:27:37Z The focus of the study is a region of enhanced ionospheric densities observed by the EISCAT Svalbard radar in the polar F-region near local magnetic noon under conditions of IMF B z <0. Multi-instrument observations, using optical, spacecraft and radar instrumentation, together with radio tomographic imaging, have been used to identify the source of the enhancement and establish the background ionospheric conditions. Soft-particle precipitation was ruled out as a candidate for the production. Tomographic observations identified a latitudinally restricted region of enhanced densities at sub-auroral latitudes, distinct from the normal mid-latitude ionosphere, which was likely to be the source. The evidence suggested that the increased sub-auroral densities were photoionisation produced at the equatorward edge of the afternoon high-latitude cell, where the plasma is exposed to sunlight for an extended period as it flows slowly sunward toward magnetic noon. It is proposed that this plasma, once in the noon sector, was drawn antisunward by the high-latitude convection toward polar latitudes where it was identified by the EISCAT Svalbard radar. The observations are discussed in terms of earlier modelling studies of polar patch densities. Key words. Ionosphere (polar ionosphere; plasma temerature; plasma convection) Text EISCAT Svalbard Copernicus Publications: E-Journals Svalbard Annales Geophysicae 22 4 1093 1102 |
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Open Polar |
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Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
The focus of the study is a region of enhanced ionospheric densities observed by the EISCAT Svalbard radar in the polar F-region near local magnetic noon under conditions of IMF B z <0. Multi-instrument observations, using optical, spacecraft and radar instrumentation, together with radio tomographic imaging, have been used to identify the source of the enhancement and establish the background ionospheric conditions. Soft-particle precipitation was ruled out as a candidate for the production. Tomographic observations identified a latitudinally restricted region of enhanced densities at sub-auroral latitudes, distinct from the normal mid-latitude ionosphere, which was likely to be the source. The evidence suggested that the increased sub-auroral densities were photoionisation produced at the equatorward edge of the afternoon high-latitude cell, where the plasma is exposed to sunlight for an extended period as it flows slowly sunward toward magnetic noon. It is proposed that this plasma, once in the noon sector, was drawn antisunward by the high-latitude convection toward polar latitudes where it was identified by the EISCAT Svalbard radar. The observations are discussed in terms of earlier modelling studies of polar patch densities. Key words. Ionosphere (polar ionosphere; plasma temerature; plasma convection) |
format |
Text |
author |
Pryse, S. E. Sims, R. W. Moen, J. Kersley, L. Lorentzen, D. Denig, W. F. |
spellingShingle |
Pryse, S. E. Sims, R. W. Moen, J. Kersley, L. Lorentzen, D. Denig, W. F. Evidence for solar-production as a source of polar-cap plasma |
author_facet |
Pryse, S. E. Sims, R. W. Moen, J. Kersley, L. Lorentzen, D. Denig, W. F. |
author_sort |
Pryse, S. E. |
title |
Evidence for solar-production as a source of polar-cap plasma |
title_short |
Evidence for solar-production as a source of polar-cap plasma |
title_full |
Evidence for solar-production as a source of polar-cap plasma |
title_fullStr |
Evidence for solar-production as a source of polar-cap plasma |
title_full_unstemmed |
Evidence for solar-production as a source of polar-cap plasma |
title_sort |
evidence for solar-production as a source of polar-cap plasma |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-22-1093-2004 https://angeo.copernicus.org/articles/22/1093/2004/ |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
EISCAT Svalbard |
genre_facet |
EISCAT Svalbard |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-22-1093-2004 https://angeo.copernicus.org/articles/22/1093/2004/ |
op_doi |
https://doi.org/10.5194/angeo-22-1093-2004 |
container_title |
Annales Geophysicae |
container_volume |
22 |
container_issue |
4 |
container_start_page |
1093 |
op_container_end_page |
1102 |
_version_ |
1766400135265255424 |