Radar studies of plasma parameters in the polar cap and the auroral zone
Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. Data from the EISCAT Svalbard radar (ESR), which covers the polar cap and cusp, and from the EISCAT Tromsø radars, which covers the auroral zone, can be used to obtain information about the el...
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Language: | English |
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UiT Norges arktiske universitet
2018
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Online Access: | https://hdl.handle.net/10037/31573 |
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ftunivtroemsoe:oai:munin.uit.no:10037/31573 2023-11-12T04:16:35+01:00 Radar studies of plasma parameters in the polar cap and the auroral zone Bjoland, Lindis Merete 2018-04-11 https://hdl.handle.net/10037/31573 eng eng UiT Norges arktiske universitet UiT The Arctic University of Norway Paper I: Bjoland, L.M., V. Belyey, U.P. Løvhaug and C. La Hoz: An evaluation of International Reference Ionosphere electron density in the polar cap and cusp using EISCAT Svalbard radar measurements, Annales Geophysicae 2016, 34 (9):751-758. Also available in Munin at https://hdl.handle.net/10037/9756 . Paper II: Bjoland, L.M., Y. Ogawa, C. Hall, M. Rietveld, U.P. Løvhaug, C. La Hoz, H. Miyaoka, Long-term variations and trends in the polar E-region, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 163 , 85-90. Also available at https://doi.org/10.1016/j.jastp.2017.02.007 . 2017. Paper III: Bjoland, L.M., Y. Ogawa, U.P. Løvhaug, High-latitude depletion regions and their dependence on geomagnetic activity (Submitted manuscript). Final paper based on this manuscript, was published in Journal of Geophysical Research, Space Physics 2021(126) 1, e2020JA028432, available in Munin at https://hdl.handle.net/10037/23876 . 978-82-8236-288-7 (trykt) og 978-82-8236-289-4 (pdf) https://hdl.handle.net/10037/31573 openAccess Copyright 2018 The Author(s) VDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437 VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Rom- og plasmafysikk: 437 DOKTOR-004 Doctoral thesis Doktorgradsavhandling 2018 ftunivtroemsoe https://doi.org/10.1016/j.jastp.2017.02.007 2023-10-18T23:07:50Z Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. Data from the EISCAT Svalbard radar (ESR), which covers the polar cap and cusp, and from the EISCAT Tromsø radars, which covers the auroral zone, can be used to obtain information about the electron density, electron- and ion temperature, and line-of-sight plasma velocity. As the ESR started operations in 1996, and the Tromsø UHF radar in 1981, the accumulated database covers several solar cycles, giving a unique overview of the polar ionosphere. In this dissertation, the accumulated EISCAT database is used to study variations in the polar ionosphere on several time scales. The dependence of ionospheric parameters on season, time of day, solar cycle and geomagnetic activity has been investigated. A comparison between the ESR data and the International Reference Ionosphere (IRI) model was conducted, in order to understand how well the IRI model reproduces the polar cap ionosphere during different ionospheric conditions. The comparison showed that the IRI model is biased towards an underestimation of the F-region polar cap electron density. Furthermore, we derived the Hall conductivity from the Tromsø UHF data and used this to search for trends in the peak height of the Hall conductivity and in the E-region ion temperature. Such trends are expected to occur due to the anthropogenic emissions of greenhouse gases. However, as these trends are expected to be very small, no conclusive trend could be found with the present instrumentation. Lastly, we studied high latitude depletion regions, and observed an early morning depletion region in the polar cap ionosphere. This region expands with increasing geomagnetic activity. ESR ion temperature measurements show a heating at approximately the same time as the depletion region, suggesting that this depletion region might be connected to ion frictional heating. Doctoral or Postdoctoral Thesis EISCAT Svalbard Tromsø University of Tromsø: Munin Open Research Archive Svalbard Tromsø Journal of Atmospheric and Solar-Terrestrial Physics 163 85 90 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437 VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Rom- og plasmafysikk: 437 DOKTOR-004 |
spellingShingle |
VDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437 VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Rom- og plasmafysikk: 437 DOKTOR-004 Bjoland, Lindis Merete Radar studies of plasma parameters in the polar cap and the auroral zone |
topic_facet |
VDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437 VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Rom- og plasmafysikk: 437 DOKTOR-004 |
description |
Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. Data from the EISCAT Svalbard radar (ESR), which covers the polar cap and cusp, and from the EISCAT Tromsø radars, which covers the auroral zone, can be used to obtain information about the electron density, electron- and ion temperature, and line-of-sight plasma velocity. As the ESR started operations in 1996, and the Tromsø UHF radar in 1981, the accumulated database covers several solar cycles, giving a unique overview of the polar ionosphere. In this dissertation, the accumulated EISCAT database is used to study variations in the polar ionosphere on several time scales. The dependence of ionospheric parameters on season, time of day, solar cycle and geomagnetic activity has been investigated. A comparison between the ESR data and the International Reference Ionosphere (IRI) model was conducted, in order to understand how well the IRI model reproduces the polar cap ionosphere during different ionospheric conditions. The comparison showed that the IRI model is biased towards an underestimation of the F-region polar cap electron density. Furthermore, we derived the Hall conductivity from the Tromsø UHF data and used this to search for trends in the peak height of the Hall conductivity and in the E-region ion temperature. Such trends are expected to occur due to the anthropogenic emissions of greenhouse gases. However, as these trends are expected to be very small, no conclusive trend could be found with the present instrumentation. Lastly, we studied high latitude depletion regions, and observed an early morning depletion region in the polar cap ionosphere. This region expands with increasing geomagnetic activity. ESR ion temperature measurements show a heating at approximately the same time as the depletion region, suggesting that this depletion region might be connected to ion frictional heating. |
format |
Doctoral or Postdoctoral Thesis |
author |
Bjoland, Lindis Merete |
author_facet |
Bjoland, Lindis Merete |
author_sort |
Bjoland, Lindis Merete |
title |
Radar studies of plasma parameters in the polar cap and the auroral zone |
title_short |
Radar studies of plasma parameters in the polar cap and the auroral zone |
title_full |
Radar studies of plasma parameters in the polar cap and the auroral zone |
title_fullStr |
Radar studies of plasma parameters in the polar cap and the auroral zone |
title_full_unstemmed |
Radar studies of plasma parameters in the polar cap and the auroral zone |
title_sort |
radar studies of plasma parameters in the polar cap and the auroral zone |
publisher |
UiT Norges arktiske universitet |
publishDate |
2018 |
url |
https://hdl.handle.net/10037/31573 |
geographic |
Svalbard Tromsø |
geographic_facet |
Svalbard Tromsø |
genre |
EISCAT Svalbard Tromsø |
genre_facet |
EISCAT Svalbard Tromsø |
op_relation |
Paper I: Bjoland, L.M., V. Belyey, U.P. Løvhaug and C. La Hoz: An evaluation of International Reference Ionosphere electron density in the polar cap and cusp using EISCAT Svalbard radar measurements, Annales Geophysicae 2016, 34 (9):751-758. Also available in Munin at https://hdl.handle.net/10037/9756 . Paper II: Bjoland, L.M., Y. Ogawa, C. Hall, M. Rietveld, U.P. Løvhaug, C. La Hoz, H. Miyaoka, Long-term variations and trends in the polar E-region, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 163 , 85-90. Also available at https://doi.org/10.1016/j.jastp.2017.02.007 . 2017. Paper III: Bjoland, L.M., Y. Ogawa, U.P. Løvhaug, High-latitude depletion regions and their dependence on geomagnetic activity (Submitted manuscript). Final paper based on this manuscript, was published in Journal of Geophysical Research, Space Physics 2021(126) 1, e2020JA028432, available in Munin at https://hdl.handle.net/10037/23876 . 978-82-8236-288-7 (trykt) og 978-82-8236-289-4 (pdf) https://hdl.handle.net/10037/31573 |
op_rights |
openAccess Copyright 2018 The Author(s) |
op_doi |
https://doi.org/10.1016/j.jastp.2017.02.007 |
container_title |
Journal of Atmospheric and Solar-Terrestrial Physics |
container_volume |
163 |
container_start_page |
85 |
op_container_end_page |
90 |
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1782333647565619200 |