HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring
Three intervals of polar patch formation, as observed by the CUTLASS Finland HF coherent radar, are presented. Simultaneous observations from a vertical ionosonde located at Longyearbyen on Svalbard, situated in the dayside convection throat region, allow for F-region plasma structuring, leading to...
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ftleicester:oai:lra.le.ac.uk:2381/36668 2023-05-15T17:08:31+02:00 HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring Milan, Stephen Eric Lester, Mark Yeoman, Timothy Kenneth 2016-02-10T11:29:19Z http://ann-geophys.net/20/487/2002/ http://hdl.handle.net/2381/36668 https://doi.org/10.5194/angeo-20-487-2002 en eng Copernicus Publications on behalf of the European Geosciences Union Annales Geophysicae, 2002, 20 (4), pp. 487-499 (13) 0992-7689 http://ann-geophys.net/20/487/2002/ http://hdl.handle.net/2381/36668 doi:10.5194/angeo-20-487-2002 1432-0576 Copyright © Author(s) 2002. This work is distributed under the Creative Commons Attribution 3.0 License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. CC-BY Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology ionosphere ionospheric irregularities plasma convection polar ionosphere CAP F-REGION FLUX-TRANSFER CONVECTION CUSP SIGNATURES CUTLASS LAYER MAGNETOPAUSE DYNAMICS Journal Article Article;Journal 2016 ftleicester https://doi.org/10.5194/angeo-20-487-2002 2019-03-22T20:21:26Z Three intervals of polar patch formation, as observed by the CUTLASS Finland HF coherent radar, are presented. Simultaneous observations from a vertical ionosonde located at Longyearbyen on Svalbard, situated in the dayside convection throat region, allow for F-region plasma structuring, leading to polar cap patch formation to be determined. Solar wind and interplanetary magnetic field (IMF) precursors of polar patch formation are investigated with MFI and SWE measurements from the Wind spacecraft. We find that in the cases studied polar cap patches are formed in response to changes in the orientation of the IMF, especially in the By component. The resultant changes in the dayside convection pattern alter the source of plasma drifting through the convection throat region into the polar cap. When the convection flow is directed predominantly polewards, high density sub-auroral or mid-latitude plasma enters the polar cap; when flow is directed zonally, low density plasma entrained in the convection return flow replaces it. This mechanism can act to significantly structure the plasma density at sub-auroral or mid-latitudes as well as in the polar cap. In winter months, polar patches appear to be produced by depletions in an otherwise high plasma density tongue of ionisation. In summer months, patches are enhancements of an otherwise low density tongue of ionisation. Peer-reviewed Publisher Version Article in Journal/Newspaper Longyearbyen Svalbard University of Leicester: Leicester Research Archive (LRA) Svalbard Longyearbyen Annales Geophysicae 20 4 487 499 |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
topic |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology ionosphere ionospheric irregularities plasma convection polar ionosphere CAP F-REGION FLUX-TRANSFER CONVECTION CUSP SIGNATURES CUTLASS LAYER MAGNETOPAUSE DYNAMICS |
spellingShingle |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology ionosphere ionospheric irregularities plasma convection polar ionosphere CAP F-REGION FLUX-TRANSFER CONVECTION CUSP SIGNATURES CUTLASS LAYER MAGNETOPAUSE DYNAMICS Milan, Stephen Eric Lester, Mark Yeoman, Timothy Kenneth HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
topic_facet |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology ionosphere ionospheric irregularities plasma convection polar ionosphere CAP F-REGION FLUX-TRANSFER CONVECTION CUSP SIGNATURES CUTLASS LAYER MAGNETOPAUSE DYNAMICS |
description |
Three intervals of polar patch formation, as observed by the CUTLASS Finland HF coherent radar, are presented. Simultaneous observations from a vertical ionosonde located at Longyearbyen on Svalbard, situated in the dayside convection throat region, allow for F-region plasma structuring, leading to polar cap patch formation to be determined. Solar wind and interplanetary magnetic field (IMF) precursors of polar patch formation are investigated with MFI and SWE measurements from the Wind spacecraft. We find that in the cases studied polar cap patches are formed in response to changes in the orientation of the IMF, especially in the By component. The resultant changes in the dayside convection pattern alter the source of plasma drifting through the convection throat region into the polar cap. When the convection flow is directed predominantly polewards, high density sub-auroral or mid-latitude plasma enters the polar cap; when flow is directed zonally, low density plasma entrained in the convection return flow replaces it. This mechanism can act to significantly structure the plasma density at sub-auroral or mid-latitudes as well as in the polar cap. In winter months, polar patches appear to be produced by depletions in an otherwise high plasma density tongue of ionisation. In summer months, patches are enhancements of an otherwise low density tongue of ionisation. Peer-reviewed Publisher Version |
format |
Article in Journal/Newspaper |
author |
Milan, Stephen Eric Lester, Mark Yeoman, Timothy Kenneth |
author_facet |
Milan, Stephen Eric Lester, Mark Yeoman, Timothy Kenneth |
author_sort |
Milan, Stephen Eric |
title |
HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
title_short |
HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
title_full |
HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
title_fullStr |
HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
title_full_unstemmed |
HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
title_sort |
hf radar polar patch formation revisited: summer and winter variations in dayside plasma structuring |
publisher |
Copernicus Publications on behalf of the European Geosciences Union |
publishDate |
2016 |
url |
http://ann-geophys.net/20/487/2002/ http://hdl.handle.net/2381/36668 https://doi.org/10.5194/angeo-20-487-2002 |
geographic |
Svalbard Longyearbyen |
geographic_facet |
Svalbard Longyearbyen |
genre |
Longyearbyen Svalbard |
genre_facet |
Longyearbyen Svalbard |
op_relation |
Annales Geophysicae, 2002, 20 (4), pp. 487-499 (13) 0992-7689 http://ann-geophys.net/20/487/2002/ http://hdl.handle.net/2381/36668 doi:10.5194/angeo-20-487-2002 1432-0576 |
op_rights |
Copyright © Author(s) 2002. This work is distributed under the Creative Commons Attribution 3.0 License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/angeo-20-487-2002 |
container_title |
Annales Geophysicae |
container_volume |
20 |
container_issue |
4 |
container_start_page |
487 |
op_container_end_page |
499 |
_version_ |
1766064285348265984 |