Interhemispheric asymmetries of neutral upwelling and ion upflow
This work addresses interhemispheric differences in cusp-related neutral density enhancements. The focus is on enhancements that are driven by Poleward Moving Auroral Forms (PMAF), which provide a repetitive sequence of soft electron precipitation to the ionosphere. Because the time-scales of the re...
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ftdoajarticles:oai:doaj.org/article:897a0121dd264fa5af92f8a277920167 2023-09-05T13:13:11+02:00 Interhemispheric asymmetries of neutral upwelling and ion upflow Marc R. Lessard Alec Damsell F. Brent Sadler Kjellmar Oksavik Lasse Clausen 2023-08-01T00:00:00Z https://doi.org/10.3389/fspas.2023.1151016 https://doaj.org/article/897a0121dd264fa5af92f8a277920167 EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/fspas.2023.1151016/full https://doaj.org/toc/2296-987X 2296-987X doi:10.3389/fspas.2023.1151016 https://doaj.org/article/897a0121dd264fa5af92f8a277920167 Frontiers in Astronomy and Space Sciences, Vol 10 (2023) neutral upwelling ion upflow interhemispheric asymmetries ionospheric density ionosphere-thermosphere coupling Astronomy QB1-991 Geophysics. Cosmic physics QC801-809 article 2023 ftdoajarticles https://doi.org/10.3389/fspas.2023.1151016 2023-08-20T00:34:47Z This work addresses interhemispheric differences in cusp-related neutral density enhancements. The focus is on enhancements that are driven by Poleward Moving Auroral Forms (PMAF), which provide a repetitive sequence of soft electron precipitation to the ionosphere. Because the time-scales of the resultant electron heating, ion upflow and neutral upwelling range from a few seconds to tens of minutes, i.e., longer than the time required for the thermosphere to return to its relaxed state, each subsequent PMAF encounters different initial conditions. With this in mind, our study investigates the role of a dark versus daylight ionosphere, using 3 different scenarios. The first case compares this effect during solar minimum at Longyearbyen, Svalbard, an ideal location for observing cusp dynamics. The second case addresses solar maximum at Longyearbyen and the third case compares Longyearbyen to its magnetically conjugate Zhongshan Station in Antarctica. We conclude 1) for each of the 3 scenarios ion upflow speeds, neutral upwelling speeds and neutral density enhancements are all significantly greater in a dark ionosphere, by perhaps as much as a factor or 2 or 3, relative to a sunlit ionosphere, 2) that upflowing ions are the driver of neutral upwelling via ion-neutral collisions (momentum transfer), with fast-moving ions transferring upward momentum to slow-moving neutrals, and 3) the ratios of neutral upflow speeds to ion upflow speeds, vnSunlit/viSunlit is the order of 0.07 for all stations (at 800 km) in the first and second cases studied, but only 0.02 at Zhongshan in the 3rd case studied, a factor of ∼3 less than the other locations. This is thought to be due to an increased thermospheric density at Zhongshan, which essentially provides a greater total mass for the upflowing ions to lift. Article in Journal/Newspaper Antarc* Antarctica Longyearbyen Svalbard Directory of Open Access Journals: DOAJ Articles Longyearbyen Svalbard Zhongshan ENVELOPE(76.371,76.371,-69.373,-69.373) Zhongshan Station ENVELOPE(76.371,76.371,-69.373,-69.373) Frontiers in Astronomy and Space Sciences 10 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
neutral upwelling ion upflow interhemispheric asymmetries ionospheric density ionosphere-thermosphere coupling Astronomy QB1-991 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
neutral upwelling ion upflow interhemispheric asymmetries ionospheric density ionosphere-thermosphere coupling Astronomy QB1-991 Geophysics. Cosmic physics QC801-809 Marc R. Lessard Alec Damsell F. Brent Sadler Kjellmar Oksavik Lasse Clausen Interhemispheric asymmetries of neutral upwelling and ion upflow |
topic_facet |
neutral upwelling ion upflow interhemispheric asymmetries ionospheric density ionosphere-thermosphere coupling Astronomy QB1-991 Geophysics. Cosmic physics QC801-809 |
description |
This work addresses interhemispheric differences in cusp-related neutral density enhancements. The focus is on enhancements that are driven by Poleward Moving Auroral Forms (PMAF), which provide a repetitive sequence of soft electron precipitation to the ionosphere. Because the time-scales of the resultant electron heating, ion upflow and neutral upwelling range from a few seconds to tens of minutes, i.e., longer than the time required for the thermosphere to return to its relaxed state, each subsequent PMAF encounters different initial conditions. With this in mind, our study investigates the role of a dark versus daylight ionosphere, using 3 different scenarios. The first case compares this effect during solar minimum at Longyearbyen, Svalbard, an ideal location for observing cusp dynamics. The second case addresses solar maximum at Longyearbyen and the third case compares Longyearbyen to its magnetically conjugate Zhongshan Station in Antarctica. We conclude 1) for each of the 3 scenarios ion upflow speeds, neutral upwelling speeds and neutral density enhancements are all significantly greater in a dark ionosphere, by perhaps as much as a factor or 2 or 3, relative to a sunlit ionosphere, 2) that upflowing ions are the driver of neutral upwelling via ion-neutral collisions (momentum transfer), with fast-moving ions transferring upward momentum to slow-moving neutrals, and 3) the ratios of neutral upflow speeds to ion upflow speeds, vnSunlit/viSunlit is the order of 0.07 for all stations (at 800 km) in the first and second cases studied, but only 0.02 at Zhongshan in the 3rd case studied, a factor of ∼3 less than the other locations. This is thought to be due to an increased thermospheric density at Zhongshan, which essentially provides a greater total mass for the upflowing ions to lift. |
format |
Article in Journal/Newspaper |
author |
Marc R. Lessard Alec Damsell F. Brent Sadler Kjellmar Oksavik Lasse Clausen |
author_facet |
Marc R. Lessard Alec Damsell F. Brent Sadler Kjellmar Oksavik Lasse Clausen |
author_sort |
Marc R. Lessard |
title |
Interhemispheric asymmetries of neutral upwelling and ion upflow |
title_short |
Interhemispheric asymmetries of neutral upwelling and ion upflow |
title_full |
Interhemispheric asymmetries of neutral upwelling and ion upflow |
title_fullStr |
Interhemispheric asymmetries of neutral upwelling and ion upflow |
title_full_unstemmed |
Interhemispheric asymmetries of neutral upwelling and ion upflow |
title_sort |
interhemispheric asymmetries of neutral upwelling and ion upflow |
publisher |
Frontiers Media S.A. |
publishDate |
2023 |
url |
https://doi.org/10.3389/fspas.2023.1151016 https://doaj.org/article/897a0121dd264fa5af92f8a277920167 |
long_lat |
ENVELOPE(76.371,76.371,-69.373,-69.373) ENVELOPE(76.371,76.371,-69.373,-69.373) |
geographic |
Longyearbyen Svalbard Zhongshan Zhongshan Station |
geographic_facet |
Longyearbyen Svalbard Zhongshan Zhongshan Station |
genre |
Antarc* Antarctica Longyearbyen Svalbard |
genre_facet |
Antarc* Antarctica Longyearbyen Svalbard |
op_source |
Frontiers in Astronomy and Space Sciences, Vol 10 (2023) |
op_relation |
https://www.frontiersin.org/articles/10.3389/fspas.2023.1151016/full https://doaj.org/toc/2296-987X 2296-987X doi:10.3389/fspas.2023.1151016 https://doaj.org/article/897a0121dd264fa5af92f8a277920167 |
op_doi |
https://doi.org/10.3389/fspas.2023.1151016 |
container_title |
Frontiers in Astronomy and Space Sciences |
container_volume |
10 |
_version_ |
1776203906144010240 |