Statistical properties of Joule heating rate, electric field and conductances at high latitudes
Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat) from 6 March to 6 April 2006. The data are from the same season (close to ve...
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Copernicus Publications
2009
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00030147 2023-05-15T16:04:50+02:00 Statistical properties of Joule heating rate, electric field and conductances at high latitudes Aikio, A. T. Selkälä, A. 2009-07 electronic https://doi.org/10.5194/angeo-27-2661-2009 https://noa.gwlb.de/receive/cop_mods_00030147 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00030101/angeo-27-2661-2009.pdf https://angeo.copernicus.org/articles/27/2661/2009/angeo-27-2661-2009.pdf eng eng Copernicus Publications Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-27-2661-2009 https://noa.gwlb.de/receive/cop_mods_00030147 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00030101/angeo-27-2661-2009.pdf https://angeo.copernicus.org/articles/27/2661/2009/angeo-27-2661-2009.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2009 ftnonlinearchiv https://doi.org/10.5194/angeo-27-2661-2009 2022-02-08T22:47:21Z Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat) from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox) and from similar sunspot conditions (about 1.5 years before the sunspot minimum) providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution. All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity. An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3). In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to auroral arcs as a result of ionosphere-magnetosphere coupling, as discussed by Aikio et al. (2004) In addition, a part of the anticorrelation may come from polarization effects inside high-conductance regions, e.g. auroral arcs. These observations confirm the speculated effect of small scale electrodynamics, which is not included in most of the global modeling efforts of Joule heating rate. Article in Journal/Newspaper EISCAT Tromsø Niedersächsisches Online-Archiv NOA Aikio ENVELOPE(26.717,26.717,67.683,67.683) Pedersen ENVELOPE(140.013,140.013,-66.668,-66.668) Tromsø Annales Geophysicae 27 7 2661 2673 |
institution |
Open Polar |
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Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Aikio, A. T. Selkälä, A. Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
topic_facet |
article Verlagsveröffentlichung |
description |
Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat) from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox) and from similar sunspot conditions (about 1.5 years before the sunspot minimum) providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution. All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity. An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3). In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to auroral arcs as a result of ionosphere-magnetosphere coupling, as discussed by Aikio et al. (2004) In addition, a part of the anticorrelation may come from polarization effects inside high-conductance regions, e.g. auroral arcs. These observations confirm the speculated effect of small scale electrodynamics, which is not included in most of the global modeling efforts of Joule heating rate. |
format |
Article in Journal/Newspaper |
author |
Aikio, A. T. Selkälä, A. |
author_facet |
Aikio, A. T. Selkälä, A. |
author_sort |
Aikio, A. T. |
title |
Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
title_short |
Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
title_full |
Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
title_fullStr |
Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
title_full_unstemmed |
Statistical properties of Joule heating rate, electric field and conductances at high latitudes |
title_sort |
statistical properties of joule heating rate, electric field and conductances at high latitudes |
publisher |
Copernicus Publications |
publishDate |
2009 |
url |
https://doi.org/10.5194/angeo-27-2661-2009 https://noa.gwlb.de/receive/cop_mods_00030147 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00030101/angeo-27-2661-2009.pdf https://angeo.copernicus.org/articles/27/2661/2009/angeo-27-2661-2009.pdf |
long_lat |
ENVELOPE(26.717,26.717,67.683,67.683) ENVELOPE(140.013,140.013,-66.668,-66.668) |
geographic |
Aikio Pedersen Tromsø |
geographic_facet |
Aikio Pedersen Tromsø |
genre |
EISCAT Tromsø |
genre_facet |
EISCAT Tromsø |
op_relation |
Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-27-2661-2009 https://noa.gwlb.de/receive/cop_mods_00030147 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00030101/angeo-27-2661-2009.pdf https://angeo.copernicus.org/articles/27/2661/2009/angeo-27-2661-2009.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/angeo-27-2661-2009 |
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Annales Geophysicae |
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27 |
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7 |
container_start_page |
2661 |
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2673 |
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1766400484787093504 |