Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase
Cosmic radio noise absorption (CNA) events associated with equatorward drifting arcs during a substorm growth phase are studied by using simultaneous optical auroral, IRIS imaging riometer and EISCAT incoherent scatter radar measurements. The CNA is generally attributed to energetic particle precipi...
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ftcopernicus:oai:publications.copernicus.org:angeo35196 2023-05-15T16:04:45+02:00 Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase Jussila, J. R. T. Aikio, A. T. Shalimov, S. Marple, S. R. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-22-1675-2004 https://angeo.copernicus.org/articles/22/1675/2004/ eng eng doi:10.5194/angeo-22-1675-2004 https://angeo.copernicus.org/articles/22/1675/2004/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-22-1675-2004 2020-07-20T16:27:37Z Cosmic radio noise absorption (CNA) events associated with equatorward drifting arcs during a substorm growth phase are studied by using simultaneous optical auroral, IRIS imaging riometer and EISCAT incoherent scatter radar measurements. The CNA is generally attributed to energetic particle precipitation in the D-region. However, it has been argued that plasma irregularities or enhanced electron temperature ( T e ) in the E-region could also produce CNA. Both of the latter mechanisms are related to intense electric fields in the ionosphere. We present two events which occur during a substorm growth phase in the evening MLT sector. In both of the events, an auroral arc is drifting equatorward, together with a region of CNA (auroral absorption bay) located on the equatorward side and outside of the arc. Both of the events are associated with enhanced D-region electron density on the equatorward side of the auroral arc, but in the second event, a region of intense electric field and enhanced electron temperature in the E-region is also located on the equatorward side of the arc. We show that in the studied events neither plasma instabilities nor enhanced T e play a significant role in producing the measured CNA, but the CNA in the vicinity of the equatorward drifting arcs is produced by D-region energetic electron precipitation. Key words. Ionosphere (auroral ionosphere; particle precipitation; electric fields and currents) Text EISCAT Copernicus Publications: E-Journals Annales Geophysicae 22 5 1675 1686 |
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Open Polar |
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Copernicus Publications: E-Journals |
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English |
description |
Cosmic radio noise absorption (CNA) events associated with equatorward drifting arcs during a substorm growth phase are studied by using simultaneous optical auroral, IRIS imaging riometer and EISCAT incoherent scatter radar measurements. The CNA is generally attributed to energetic particle precipitation in the D-region. However, it has been argued that plasma irregularities or enhanced electron temperature ( T e ) in the E-region could also produce CNA. Both of the latter mechanisms are related to intense electric fields in the ionosphere. We present two events which occur during a substorm growth phase in the evening MLT sector. In both of the events, an auroral arc is drifting equatorward, together with a region of CNA (auroral absorption bay) located on the equatorward side and outside of the arc. Both of the events are associated with enhanced D-region electron density on the equatorward side of the auroral arc, but in the second event, a region of intense electric field and enhanced electron temperature in the E-region is also located on the equatorward side of the arc. We show that in the studied events neither plasma instabilities nor enhanced T e play a significant role in producing the measured CNA, but the CNA in the vicinity of the equatorward drifting arcs is produced by D-region energetic electron precipitation. Key words. Ionosphere (auroral ionosphere; particle precipitation; electric fields and currents) |
format |
Text |
author |
Jussila, J. R. T. Aikio, A. T. Shalimov, S. Marple, S. R. |
spellingShingle |
Jussila, J. R. T. Aikio, A. T. Shalimov, S. Marple, S. R. Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
author_facet |
Jussila, J. R. T. Aikio, A. T. Shalimov, S. Marple, S. R. |
author_sort |
Jussila, J. R. T. |
title |
Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
title_short |
Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
title_full |
Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
title_fullStr |
Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
title_full_unstemmed |
Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
title_sort |
cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-22-1675-2004 https://angeo.copernicus.org/articles/22/1675/2004/ |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-22-1675-2004 https://angeo.copernicus.org/articles/22/1675/2004/ |
op_doi |
https://doi.org/10.5194/angeo-22-1675-2004 |
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Annales Geophysicae |
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22 |
container_issue |
5 |
container_start_page |
1675 |
op_container_end_page |
1686 |
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1766400383397134336 |