Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm
The dynamics of the polar cap and the auroral oval are examined in the evening sector during a substorm period on 25 November 2000 by using measurements of the EISCAT incoherent scatter radars, the north-south chain of the MIRACLE magnetometer network, and the Polar UV Imager. The location of the po...
Published in: | Annales Geophysicae |
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Language: | English |
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Department of Physical Sciences, University of Oulu, Finland
2009
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ftumeauniv:oai:DiVA.org:umu-102620 2023-10-09T21:51:08+02:00 Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm Pitkänen, Timo Aikio, Anita T. Kozlovsky, Alexander Amm, Olaf 2009 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102620 https://doi.org/10.5194/angeo-27-2157-2009 eng eng Department of Physical Sciences, University of Oulu, Finland Sodankylä Geophysical Observatory, Sodankylä, Finla Finnish Meteorological Institute, Helsinki, Finland Copernicus Publications Annales Geophysicae, 0992-7689, 2009, 27, s. 2157-2171 orcid:0000-0002-5681-0366 http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102620 doi:10.5194/angeo-27-2157-2009 info:eu-repo/semantics/openAccess Ionosphere (Polar ionosphere) Magnetospheric physics (Auroral phenomena Magnetosphereionosphere interactions) Fusion Plasma and Space Physics plasma och rymdfysik Article in journal info:eu-repo/semantics/article text 2009 ftumeauniv https://doi.org/10.5194/angeo-27-2157-2009 2023-09-22T13:51:37Z The dynamics of the polar cap and the auroral oval are examined in the evening sector during a substorm period on 25 November 2000 by using measurements of the EISCAT incoherent scatter radars, the north-south chain of the MIRACLE magnetometer network, and the Polar UV Imager. The location of the polar cap boundary (PCB) is estimated from electron temperature measurements by the mainland low-elevation EISCAT VHF radar and the 42m antenna of the EISCAT Svalbard radar. A comparison to the poleward auroral emission (PAE) boundary by the Polar UV Imager shows that in this event the PAE boundary is typically located 0.7 of magnetic latitude poleward of the PCB by EISCAT. The convection reversal boundary (CRB) is determined from the 2-D plasma drift velocity extracted from the dual-beam VHF data. The CRB is located 0.5–1 equatorward of the PCB indicating the existence of viscous-driven antisunward convection on closed field lines. East-west equivalent electrojets are calculated from the MIRACLE magnetometer data by the 1-D upward continuation method. In the substorm growth phase, electrojets together with the polar cap boundary move gradually equatorwards. During the substorm expansion phase, the Harang discontinuity (HD) region expands to the MLT sector of EISCAT. In the recovery phase the PCB follows the poleward edge of the westward electrojet. The local ionospheric reconnection electric field is calculated by using the measured plasma velocities in the vicinity of the polar cap boundary. During the substorm growth phase, values between 0 and 10 mV/m are found. During the late expansion and recovery phase, the reconnection electric field has temporal variations with periods of 7–27 min and values from 0 to 40 mV/m. It is shown quantitatively, for the first time to our knowledge, that intensifications in the local reconnection electric field correlate with appearance of auroral poleward boundary intensifications (PBIs) in the same MLT sector. The results suggest that PBIs (typically 1.5 h MLT wide) are a consequence ... Article in Journal/Newspaper EISCAT Svalbard Umeå University: Publications (DiVA) Svalbard Annales Geophysicae 27 5 2157 2171 |
institution |
Open Polar |
collection |
Umeå University: Publications (DiVA) |
op_collection_id |
ftumeauniv |
language |
English |
topic |
Ionosphere (Polar ionosphere) Magnetospheric physics (Auroral phenomena Magnetosphereionosphere interactions) Fusion Plasma and Space Physics plasma och rymdfysik |
spellingShingle |
Ionosphere (Polar ionosphere) Magnetospheric physics (Auroral phenomena Magnetosphereionosphere interactions) Fusion Plasma and Space Physics plasma och rymdfysik Pitkänen, Timo Aikio, Anita T. Kozlovsky, Alexander Amm, Olaf Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
topic_facet |
Ionosphere (Polar ionosphere) Magnetospheric physics (Auroral phenomena Magnetosphereionosphere interactions) Fusion Plasma and Space Physics plasma och rymdfysik |
description |
The dynamics of the polar cap and the auroral oval are examined in the evening sector during a substorm period on 25 November 2000 by using measurements of the EISCAT incoherent scatter radars, the north-south chain of the MIRACLE magnetometer network, and the Polar UV Imager. The location of the polar cap boundary (PCB) is estimated from electron temperature measurements by the mainland low-elevation EISCAT VHF radar and the 42m antenna of the EISCAT Svalbard radar. A comparison to the poleward auroral emission (PAE) boundary by the Polar UV Imager shows that in this event the PAE boundary is typically located 0.7 of magnetic latitude poleward of the PCB by EISCAT. The convection reversal boundary (CRB) is determined from the 2-D plasma drift velocity extracted from the dual-beam VHF data. The CRB is located 0.5–1 equatorward of the PCB indicating the existence of viscous-driven antisunward convection on closed field lines. East-west equivalent electrojets are calculated from the MIRACLE magnetometer data by the 1-D upward continuation method. In the substorm growth phase, electrojets together with the polar cap boundary move gradually equatorwards. During the substorm expansion phase, the Harang discontinuity (HD) region expands to the MLT sector of EISCAT. In the recovery phase the PCB follows the poleward edge of the westward electrojet. The local ionospheric reconnection electric field is calculated by using the measured plasma velocities in the vicinity of the polar cap boundary. During the substorm growth phase, values between 0 and 10 mV/m are found. During the late expansion and recovery phase, the reconnection electric field has temporal variations with periods of 7–27 min and values from 0 to 40 mV/m. It is shown quantitatively, for the first time to our knowledge, that intensifications in the local reconnection electric field correlate with appearance of auroral poleward boundary intensifications (PBIs) in the same MLT sector. The results suggest that PBIs (typically 1.5 h MLT wide) are a consequence ... |
format |
Article in Journal/Newspaper |
author |
Pitkänen, Timo Aikio, Anita T. Kozlovsky, Alexander Amm, Olaf |
author_facet |
Pitkänen, Timo Aikio, Anita T. Kozlovsky, Alexander Amm, Olaf |
author_sort |
Pitkänen, Timo |
title |
Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
title_short |
Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
title_full |
Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
title_fullStr |
Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
title_full_unstemmed |
Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
title_sort |
reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm |
publisher |
Department of Physical Sciences, University of Oulu, Finland |
publishDate |
2009 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102620 https://doi.org/10.5194/angeo-27-2157-2009 |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
EISCAT Svalbard |
genre_facet |
EISCAT Svalbard |
op_relation |
Annales Geophysicae, 0992-7689, 2009, 27, s. 2157-2171 orcid:0000-0002-5681-0366 http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102620 doi:10.5194/angeo-27-2157-2009 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/angeo-27-2157-2009 |
container_title |
Annales Geophysicae |
container_volume |
27 |
container_issue |
5 |
container_start_page |
2157 |
op_container_end_page |
2171 |
_version_ |
1779314217525968896 |