Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux
We investigate the origin of low-energy (Ek < 10 eV) ion upflows in Earth's low-altitude dayside cusp region. The Cusp-2002 sounding rocket flew from Ny Ålesund, Svalbard, on 14 December 2002, carrying plasma and field instrumentation to an altitude of 768 km. The Suprathermal Ion Imager, a...
Published in: | Journal of Geophysical Research: Space Physics |
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Online Access: | http://onlinelibrary.wiley.com/doi/10.1029/2009JA015006/abstract http://hdl.handle.net/2381/8216 https://doi.org/10.1029/2009JA015006 |
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ftleicester:oai:lra.le.ac.uk:2381/8216 2023-05-15T17:48:28+02:00 Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux Burchill, J. K. Knudsen, D. J. Clemmons, J. H. Oksavik, K. Pfaff, R. F. Steigies, C. T. Yau, A. W. Yeoman, Tim K. 2010-07-13T15:53:35Z http://onlinelibrary.wiley.com/doi/10.1029/2009JA015006/abstract http://hdl.handle.net/2381/8216 https://doi.org/10.1029/2009JA015006 en eng American Geophysical Union (AGU) Radio and Space Plasma Physics Journal of Geophysical Research: Space Physics, 2010, 115, A05206. 0148-0227 http://onlinelibrary.wiley.com/doi/10.1029/2009JA015006/abstract http://hdl.handle.net/2381/8216 doi:10.1029/2009JA015006 This paper was published as Journal of Geophysical Research: Space Physics, 2010, 115, A05206. It is also available from http://www.agu.org/pubs/crossref/2010/2009JA015006.shtml. Doi:10.1029/2009JA015006 Article 2010 ftleicester https://doi.org/10.1029/2009JA015006 2019-03-22T20:14:13Z We investigate the origin of low-energy (Ek < 10 eV) ion upflows in Earth's low-altitude dayside cusp region. The Cusp-2002 sounding rocket flew from Ny Ålesund, Svalbard, on 14 December 2002, carrying plasma and field instrumentation to an altitude of 768 km. The Suprathermal Ion Imager, a two-dimensional energy/arrival angle spectrograph, observed large (>500 m s−1) ion upflows within the cusp at altitudes between 640 km and 768 km. We report a significant correlation between ion upflow and precipitating magnetosheath electron energy flux in this altitude range. There is only very weak correlation between upflow and wave power in the VLF band. We find a small negative correlation between upflow and the magnitude of the DC electric field for fields less than about 70 mV m−1. The apparent relation between upflow and electron energy flux suggests a mechanism whereby ions are accelerated by parallel electric fields that are established by the soft electrons. Significant ion upflows are not observed for electron energy fluxes less than about 1010 eV cm−2 s−1. The lack of correspondence between ∣E∣ and upflow on the one hand, and wave power and upflow on the other, does not rule out these processes but implies that, if operating, they are not local to the measurement region. We also observe narrow regions of large ion downflow that imply either a rebalancing of the ionosphere toward a low-Te equilibrium during which gravity dominates over the pressure gradients or a convection of the upflowing ions away from the precipitation region, outside of which the ions must fall back into equilibrium at lower altitudes. Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard University of Leicester: Leicester Research Archive (LRA) Svalbard Ny-Ålesund Journal of Geophysical Research: Space Physics 115 A5 n/a n/a |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
description |
We investigate the origin of low-energy (Ek < 10 eV) ion upflows in Earth's low-altitude dayside cusp region. The Cusp-2002 sounding rocket flew from Ny Ålesund, Svalbard, on 14 December 2002, carrying plasma and field instrumentation to an altitude of 768 km. The Suprathermal Ion Imager, a two-dimensional energy/arrival angle spectrograph, observed large (>500 m s−1) ion upflows within the cusp at altitudes between 640 km and 768 km. We report a significant correlation between ion upflow and precipitating magnetosheath electron energy flux in this altitude range. There is only very weak correlation between upflow and wave power in the VLF band. We find a small negative correlation between upflow and the magnitude of the DC electric field for fields less than about 70 mV m−1. The apparent relation between upflow and electron energy flux suggests a mechanism whereby ions are accelerated by parallel electric fields that are established by the soft electrons. Significant ion upflows are not observed for electron energy fluxes less than about 1010 eV cm−2 s−1. The lack of correspondence between ∣E∣ and upflow on the one hand, and wave power and upflow on the other, does not rule out these processes but implies that, if operating, they are not local to the measurement region. We also observe narrow regions of large ion downflow that imply either a rebalancing of the ionosphere toward a low-Te equilibrium during which gravity dominates over the pressure gradients or a convection of the upflowing ions away from the precipitation region, outside of which the ions must fall back into equilibrium at lower altitudes. |
format |
Article in Journal/Newspaper |
author |
Burchill, J. K. Knudsen, D. J. Clemmons, J. H. Oksavik, K. Pfaff, R. F. Steigies, C. T. Yau, A. W. Yeoman, Tim K. |
spellingShingle |
Burchill, J. K. Knudsen, D. J. Clemmons, J. H. Oksavik, K. Pfaff, R. F. Steigies, C. T. Yau, A. W. Yeoman, Tim K. Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
author_facet |
Burchill, J. K. Knudsen, D. J. Clemmons, J. H. Oksavik, K. Pfaff, R. F. Steigies, C. T. Yau, A. W. Yeoman, Tim K. |
author_sort |
Burchill, J. K. |
title |
Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
title_short |
Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
title_full |
Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
title_fullStr |
Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
title_full_unstemmed |
Thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
title_sort |
thermal ion upflow in the cusp ionosphere and its dependence on soft electron energy flux |
publisher |
American Geophysical Union (AGU) |
publishDate |
2010 |
url |
http://onlinelibrary.wiley.com/doi/10.1029/2009JA015006/abstract http://hdl.handle.net/2381/8216 https://doi.org/10.1029/2009JA015006 |
geographic |
Svalbard Ny-Ålesund |
geographic_facet |
Svalbard Ny-Ålesund |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_relation |
Radio and Space Plasma Physics Journal of Geophysical Research: Space Physics, 2010, 115, A05206. 0148-0227 http://onlinelibrary.wiley.com/doi/10.1029/2009JA015006/abstract http://hdl.handle.net/2381/8216 doi:10.1029/2009JA015006 |
op_rights |
This paper was published as Journal of Geophysical Research: Space Physics, 2010, 115, A05206. It is also available from http://www.agu.org/pubs/crossref/2010/2009JA015006.shtml. Doi:10.1029/2009JA015006 |
op_doi |
https://doi.org/10.1029/2009JA015006 |
container_title |
Journal of Geophysical Research: Space Physics |
container_volume |
115 |
container_issue |
A5 |
container_start_page |
n/a |
op_container_end_page |
n/a |
_version_ |
1766154551556046848 |