Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature
Geosynchronous Los Alamos National Laboratory (LANL-97A) satellite particle data, riometer data, and radio wave data recorded at high geomagnetic latitudes in the region south of Australia and New Zealand are used to perform the first complete modeling study of the effect of substorm electron precip...
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American Geophysical Union
2008
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ftunivnewcastnsw:uon:4834 2023-05-15T13:54:56+02:00 Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature Clilverd, Mark A. Rodger, Craig J. Menk, Frederick W. Brundell, James Bähr, John Cobbett, Neil Moffat-Griffin, Tracy Kavanagh, Andrew J. Seppälä, Annika Thomson, Neil R. Friedel, Reiner H. W. The University of Newcastle. Faculty of Science & Information Technology, School of Mathematical and Physical Sciences 2008 http://hdl.handle.net/1959.13/41495 eng eng American Geophysical Union Journal of Geophysical Research Vol. 113 10.1029/2008JA013220 substorm electron precipitation ionosphere/magnetosphere interactions magnetospheric physics journal article 2008 ftunivnewcastnsw 2018-07-27T00:27:14Z Geosynchronous Los Alamos National Laboratory (LANL-97A) satellite particle data, riometer data, and radio wave data recorded at high geomagnetic latitudes in the region south of Australia and New Zealand are used to perform the first complete modeling study of the effect of substorm electron precipitation fluxes on low-frequency radio wave propagation conditions associated with dispersionless substorm injection events. We find that the precipitated electron energy spectrum is consistent with an e-folding energy of 50 keV for energies <400 keV but also contains higher fluxes of electrons from 400 to 2000 keV. To reproduce the peak subionospheric radio wave absorption signatures seen at Casey (Australian Antarctic Division), and the peak riometer absorption observed at Macquarie Island, requires the precipitation of 50–90% of the peak fluxes observed by LANL-97A. Additionally, there is a concurrent and previously unreported substorm signature at L < 2.8, observed as a substorm-associated phase advance on radio waves propagating between Australia and New Zealand. Two mechanisms are discussed to explain the phase advances. We find that the most likely mechanism is the triggering of wave-induced electron precipitation caused by waves enhanced in the plasmasphere during the substorm and that either plasmaspheric hiss waves or electromagnetic ion cyclotron waves are a potential source capable of precipitating the type of high-energy electron spectrum required. However, the presence of these waves at such low L shells has not been confirmed in this study. Article in Journal/Newspaper Antarc* Antarctic Australian Antarctic Division Macquarie Island NOVA: The University of Newcastle Research Online (Australia) Antarctic New Zealand |
institution |
Open Polar |
collection |
NOVA: The University of Newcastle Research Online (Australia) |
op_collection_id |
ftunivnewcastnsw |
language |
English |
topic |
substorm electron precipitation ionosphere/magnetosphere interactions magnetospheric physics |
spellingShingle |
substorm electron precipitation ionosphere/magnetosphere interactions magnetospheric physics Clilverd, Mark A. Rodger, Craig J. Menk, Frederick W. Brundell, James Bähr, John Cobbett, Neil Moffat-Griffin, Tracy Kavanagh, Andrew J. Seppälä, Annika Thomson, Neil R. Friedel, Reiner H. W. Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
topic_facet |
substorm electron precipitation ionosphere/magnetosphere interactions magnetospheric physics |
description |
Geosynchronous Los Alamos National Laboratory (LANL-97A) satellite particle data, riometer data, and radio wave data recorded at high geomagnetic latitudes in the region south of Australia and New Zealand are used to perform the first complete modeling study of the effect of substorm electron precipitation fluxes on low-frequency radio wave propagation conditions associated with dispersionless substorm injection events. We find that the precipitated electron energy spectrum is consistent with an e-folding energy of 50 keV for energies <400 keV but also contains higher fluxes of electrons from 400 to 2000 keV. To reproduce the peak subionospheric radio wave absorption signatures seen at Casey (Australian Antarctic Division), and the peak riometer absorption observed at Macquarie Island, requires the precipitation of 50–90% of the peak fluxes observed by LANL-97A. Additionally, there is a concurrent and previously unreported substorm signature at L < 2.8, observed as a substorm-associated phase advance on radio waves propagating between Australia and New Zealand. Two mechanisms are discussed to explain the phase advances. We find that the most likely mechanism is the triggering of wave-induced electron precipitation caused by waves enhanced in the plasmasphere during the substorm and that either plasmaspheric hiss waves or electromagnetic ion cyclotron waves are a potential source capable of precipitating the type of high-energy electron spectrum required. However, the presence of these waves at such low L shells has not been confirmed in this study. |
author2 |
The University of Newcastle. Faculty of Science & Information Technology, School of Mathematical and Physical Sciences |
format |
Article in Journal/Newspaper |
author |
Clilverd, Mark A. Rodger, Craig J. Menk, Frederick W. Brundell, James Bähr, John Cobbett, Neil Moffat-Griffin, Tracy Kavanagh, Andrew J. Seppälä, Annika Thomson, Neil R. Friedel, Reiner H. W. |
author_facet |
Clilverd, Mark A. Rodger, Craig J. Menk, Frederick W. Brundell, James Bähr, John Cobbett, Neil Moffat-Griffin, Tracy Kavanagh, Andrew J. Seppälä, Annika Thomson, Neil R. Friedel, Reiner H. W. |
author_sort |
Clilverd, Mark A. |
title |
Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
title_short |
Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
title_full |
Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
title_fullStr |
Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
title_full_unstemmed |
Energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
title_sort |
energetic electron precipitation during substorm injection events: high-latitude fluxes and an unexpected midlatitude signature |
publisher |
American Geophysical Union |
publishDate |
2008 |
url |
http://hdl.handle.net/1959.13/41495 |
geographic |
Antarctic New Zealand |
geographic_facet |
Antarctic New Zealand |
genre |
Antarc* Antarctic Australian Antarctic Division Macquarie Island |
genre_facet |
Antarc* Antarctic Australian Antarctic Division Macquarie Island |
op_relation |
Journal of Geophysical Research Vol. 113 10.1029/2008JA013220 |
_version_ |
1766261149426253824 |