Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study
A period (08:10–14:40 MLT, 11 February 1997) of enhanced electron density in the D- and E-regions is investigated using EISCAT, IRIS and other complementary instruments. The precipitation is determined to be due to substorm processes occurring close to magnetic midnight. Energetic electrons drift ea...
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European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)
2016
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Online Access: | http://www.ann-geophys.net/20/1321/2002/ http://hdl.handle.net/2381/36461 https://doi.org/10.5194/angeo-20-1321-2002 |
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ftleicester:oai:lra.le.ac.uk:2381/36461 2023-05-15T16:04:39+02:00 Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study Kavanagh, A. J. Honary, F. McCrea, I. W. Donovan, E. Woodfield, E. E. Manninen, J. Anderson, P. C. 2016-02-01T09:23:10Z http://www.ann-geophys.net/20/1321/2002/ http://hdl.handle.net/2381/36461 https://doi.org/10.5194/angeo-20-1321-2002 en eng European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany) Annales Geophysicae, 20, 1321-1334, 2002 0992-7689 http://www.ann-geophys.net/20/1321/2002/ http://hdl.handle.net/2381/36461 doi:10.5194/angeo-20-1321-2002 1432-0576 © Author(s) 2002. This work is distributed under the Creative Commons Attribution 3.0 License. CC-BY Ionosphere (auroral ionosphere particle precipitation) Magnetospheric physics (storms and substorms) Journal Article 2016 ftleicester https://doi.org/10.5194/angeo-20-1321-2002 2019-03-22T20:21:26Z A period (08:10–14:40 MLT, 11 February 1997) of enhanced electron density in the D- and E-regions is investigated using EISCAT, IRIS and other complementary instruments. The precipitation is determined to be due to substorm processes occurring close to magnetic midnight. Energetic electrons drift eastward after substorm injection and precipitate in the morning sector. The precipitation is triggered by small pulses in the solar wind pressure, which drive wave particle interactions. The characteristic energy of precipitation is inferred from drift timing on different L-shells and apparently verified by EISCAT measurements. The IMF influence on the precipitation in the auroral zone is also briefly discussed. A large change in the precipitation spectrum is attributed to increased numbers of ions and much reduced electron fluxes. These are detected by a close passing DMSP satellite. The possibility that these ions are from the low latitude boundary layer (LLBL) is discussed with reference to structured narrow band Pc1 waves observed by a search coil magnetometer, co-located with IRIS. The intensity of the waves grows with increased distance equatorward of the cusp position (determined by both satellite and HF radar), contrary to expectations if the precipitation is linked to the LLBL. It is suggested that the ion precipitation is, instead, due to the recovery phase of a small geomagnetic storm, following on from very active conditions. The movement of absorption in the later stages of the event is compared with observations of the ionospheric convection velocities. A good agreement is found to exist in this time interval suggesting that E × B drift has become the dominant drift mechanism over the gradient-curvature drift separation of the moving absorption patches observed at the beginning of the morning precipitation event. AJK is indebted to both PPARC and the Rutherford Appleton Laboratories for a CASE research studentship. Peer-reviewed Publisher Version Article in Journal/Newspaper EISCAT University of Leicester: Leicester Research Archive (LRA) Annales Geophysicae 20 9 1321 1334 |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
topic |
Ionosphere (auroral ionosphere particle precipitation) Magnetospheric physics (storms and substorms) |
spellingShingle |
Ionosphere (auroral ionosphere particle precipitation) Magnetospheric physics (storms and substorms) Kavanagh, A. J. Honary, F. McCrea, I. W. Donovan, E. Woodfield, E. E. Manninen, J. Anderson, P. C. Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
topic_facet |
Ionosphere (auroral ionosphere particle precipitation) Magnetospheric physics (storms and substorms) |
description |
A period (08:10–14:40 MLT, 11 February 1997) of enhanced electron density in the D- and E-regions is investigated using EISCAT, IRIS and other complementary instruments. The precipitation is determined to be due to substorm processes occurring close to magnetic midnight. Energetic electrons drift eastward after substorm injection and precipitate in the morning sector. The precipitation is triggered by small pulses in the solar wind pressure, which drive wave particle interactions. The characteristic energy of precipitation is inferred from drift timing on different L-shells and apparently verified by EISCAT measurements. The IMF influence on the precipitation in the auroral zone is also briefly discussed. A large change in the precipitation spectrum is attributed to increased numbers of ions and much reduced electron fluxes. These are detected by a close passing DMSP satellite. The possibility that these ions are from the low latitude boundary layer (LLBL) is discussed with reference to structured narrow band Pc1 waves observed by a search coil magnetometer, co-located with IRIS. The intensity of the waves grows with increased distance equatorward of the cusp position (determined by both satellite and HF radar), contrary to expectations if the precipitation is linked to the LLBL. It is suggested that the ion precipitation is, instead, due to the recovery phase of a small geomagnetic storm, following on from very active conditions. The movement of absorption in the later stages of the event is compared with observations of the ionospheric convection velocities. A good agreement is found to exist in this time interval suggesting that E × B drift has become the dominant drift mechanism over the gradient-curvature drift separation of the moving absorption patches observed at the beginning of the morning precipitation event. AJK is indebted to both PPARC and the Rutherford Appleton Laboratories for a CASE research studentship. Peer-reviewed Publisher Version |
format |
Article in Journal/Newspaper |
author |
Kavanagh, A. J. Honary, F. McCrea, I. W. Donovan, E. Woodfield, E. E. Manninen, J. Anderson, P. C. |
author_facet |
Kavanagh, A. J. Honary, F. McCrea, I. W. Donovan, E. Woodfield, E. E. Manninen, J. Anderson, P. C. |
author_sort |
Kavanagh, A. J. |
title |
Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
title_short |
Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
title_full |
Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
title_fullStr |
Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
title_full_unstemmed |
Substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
title_sort |
substorm related changes in precipitation in the dayside auroral zone – a multi instrument case study |
publisher |
European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany) |
publishDate |
2016 |
url |
http://www.ann-geophys.net/20/1321/2002/ http://hdl.handle.net/2381/36461 https://doi.org/10.5194/angeo-20-1321-2002 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
Annales Geophysicae, 20, 1321-1334, 2002 0992-7689 http://www.ann-geophys.net/20/1321/2002/ http://hdl.handle.net/2381/36461 doi:10.5194/angeo-20-1321-2002 1432-0576 |
op_rights |
© Author(s) 2002. This work is distributed under the Creative Commons Attribution 3.0 License. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/angeo-20-1321-2002 |
container_title |
Annales Geophysicae |
container_volume |
20 |
container_issue |
9 |
container_start_page |
1321 |
op_container_end_page |
1334 |
_version_ |
1766400261702549504 |