Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems
Simultaneous observations with the IRIS, DASI and EISCAT systems are employed in the study of the spatial distribution and temporal evolution of auroral forms and precipitation regions during substorm activity. The evolution of the spectrum of precipitating electrons above Tromsø during the various...
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ftdoajarticles:oai:doaj.org/article:341f5f9786e74d7c9dbd46a4bd8428c0 2023-05-15T16:04:33+02:00 Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems C. F. del Pozo F. Honary N. Stamatiou M. J. Kosch 2002-09-01T00:00:00Z https://doi.org/10.5194/angeo-20-1361-2002 https://doaj.org/article/341f5f9786e74d7c9dbd46a4bd8428c0 EN eng Copernicus Publications https://www.ann-geophys.net/20/1361/2002/angeo-20-1361-2002.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-20-1361-2002 0992-7689 1432-0576 https://doaj.org/article/341f5f9786e74d7c9dbd46a4bd8428c0 Annales Geophysicae, Vol 20, Pp 1361-1375 (2002) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2002 ftdoajarticles https://doi.org/10.5194/angeo-20-1361-2002 2022-12-31T03:13:22Z Simultaneous observations with the IRIS, DASI and EISCAT systems are employed in the study of the spatial distribution and temporal evolution of auroral forms and precipitation regions during substorm activity. The evolution of the spectrum of precipitating electrons above Tromsø during the various phases of substorms is discussed. The flux-energy spectrum in the 1–320 keV range is derived from EISCAT electron density profiles in the 70–140 km altitude range. At the late growth phase the precipitation flux at the higher energies increases faster than at the lower energies. The flux is always greater in the lower energy side of the spectrum and reaches a maximum a few minutes after substorm onset, then it decays while the spectrum narrows. The systematic analysis of 2-D structures corresponding with well-defined optical and absorption features is also discussed. The orientation, characteristic lengths (elongation and width) and the gravity centre of these spatial features are determined. The statistical analysis of centre position and the sizes of the corresponding signatures is presented. When substorm onset falls within the common field of view, there is a close correspondence between the optical and the absorption signatures of the auroral forms, as well as in their over-all north-south motion characteristic of the various phases of the substorm. Optical signatures of arcs are more evenly distributed in space, being narrower and elongated along the L-shells, while the absorption regions appear more structured and patchy, although generally following the arcs’ shape and alignment. Cross-correlation of the time series of maximum absorption and maximum green-line emission is very high and seems to show a systematic delay of absorption relative to optical emission. Time delays are generally larger for disturbed conditions (40 to 60 s) than for moderately active conditions (10 to 20 s). Key words. Interplanetary physics (energetic particles) – Ionosphere (auroral ionosphere; ionosphere–magnetosphere interactions) Article in Journal/Newspaper EISCAT Tromsø Directory of Open Access Journals: DOAJ Articles Tromsø Narrows The ENVELOPE(-67.167,-67.167,-67.617,-67.617) Annales Geophysicae 20 9 1361 1375 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 C. F. del Pozo F. Honary N. Stamatiou M. J. Kosch Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Simultaneous observations with the IRIS, DASI and EISCAT systems are employed in the study of the spatial distribution and temporal evolution of auroral forms and precipitation regions during substorm activity. The evolution of the spectrum of precipitating electrons above Tromsø during the various phases of substorms is discussed. The flux-energy spectrum in the 1–320 keV range is derived from EISCAT electron density profiles in the 70–140 km altitude range. At the late growth phase the precipitation flux at the higher energies increases faster than at the lower energies. The flux is always greater in the lower energy side of the spectrum and reaches a maximum a few minutes after substorm onset, then it decays while the spectrum narrows. The systematic analysis of 2-D structures corresponding with well-defined optical and absorption features is also discussed. The orientation, characteristic lengths (elongation and width) and the gravity centre of these spatial features are determined. The statistical analysis of centre position and the sizes of the corresponding signatures is presented. When substorm onset falls within the common field of view, there is a close correspondence between the optical and the absorption signatures of the auroral forms, as well as in their over-all north-south motion characteristic of the various phases of the substorm. Optical signatures of arcs are more evenly distributed in space, being narrower and elongated along the L-shells, while the absorption regions appear more structured and patchy, although generally following the arcs’ shape and alignment. Cross-correlation of the time series of maximum absorption and maximum green-line emission is very high and seems to show a systematic delay of absorption relative to optical emission. Time delays are generally larger for disturbed conditions (40 to 60 s) than for moderately active conditions (10 to 20 s). Key words. Interplanetary physics (energetic particles) – Ionosphere (auroral ionosphere; ionosphere–magnetosphere interactions) |
format |
Article in Journal/Newspaper |
author |
C. F. del Pozo F. Honary N. Stamatiou M. J. Kosch |
author_facet |
C. F. del Pozo F. Honary N. Stamatiou M. J. Kosch |
author_sort |
C. F. del Pozo |
title |
Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
title_short |
Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
title_full |
Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
title_fullStr |
Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
title_full_unstemmed |
Study of auroral forms and electron precipitation with the IRIS, DASI and EISCAT systems |
title_sort |
study of auroral forms and electron precipitation with the iris, dasi and eiscat systems |
publisher |
Copernicus Publications |
publishDate |
2002 |
url |
https://doi.org/10.5194/angeo-20-1361-2002 https://doaj.org/article/341f5f9786e74d7c9dbd46a4bd8428c0 |
long_lat |
ENVELOPE(-67.167,-67.167,-67.617,-67.617) |
geographic |
Tromsø Narrows The |
geographic_facet |
Tromsø Narrows The |
genre |
EISCAT Tromsø |
genre_facet |
EISCAT Tromsø |
op_source |
Annales Geophysicae, Vol 20, Pp 1361-1375 (2002) |
op_relation |
https://www.ann-geophys.net/20/1361/2002/angeo-20-1361-2002.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-20-1361-2002 0992-7689 1432-0576 https://doaj.org/article/341f5f9786e74d7c9dbd46a4bd8428c0 |
op_doi |
https://doi.org/10.5194/angeo-20-1361-2002 |
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Annales Geophysicae |
container_volume |
20 |
container_issue |
9 |
container_start_page |
1361 |
op_container_end_page |
1375 |
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1766400131527081984 |