On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm
A -190-nT negative bay in the geomagnetic X component measured at Macquarie Island ( -65° L ) showed that an ionospheric substorm occurred during 09:58 to 11:10 UT on 27 February 2000. Signatures of an auroral westward flow channel (AWFC) were observed nearly simultaneously in the backscatter power,...
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ftdoajarticles:oai:doaj.org/article:f019c56fde674e6aade4cec5548025b1 2023-05-15T17:09:59+02:00 On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm M. L. Parkinson M. Pinnock H. Ye M. R. Hairston J. C. Devlin P. L. Dyson R. J. Morris P. Ponomarenko 2003-04-01T00:00:00Z https://doi.org/10.5194/angeo-21-893-2003 https://doaj.org/article/f019c56fde674e6aade4cec5548025b1 EN eng Copernicus Publications https://www.ann-geophys.net/21/893/2003/angeo-21-893-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-893-2003 0992-7689 1432-0576 https://doaj.org/article/f019c56fde674e6aade4cec5548025b1 Annales Geophysicae, Vol 21, Pp 893-913 (2003) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2003 ftdoajarticles https://doi.org/10.5194/angeo-21-893-2003 2022-12-31T10:44:46Z A -190-nT negative bay in the geomagnetic X component measured at Macquarie Island ( -65° L ) showed that an ionospheric substorm occurred during 09:58 to 11:10 UT on 27 February 2000. Signatures of an auroral westward flow channel (AWFC) were observed nearly simultaneously in the backscatter power, LOS Doppler velocity, and Doppler spectral width measured using the Tasman International Geospace Environment Radar (TIGER), a Southern Hemisphere HF SuperDARN radar. Many of the characteristics of the AWFC were similar to those occurring during a polarisation jet (PJ), or subauroral ion drift (SAID) event, and suggest that it may have been a pre-cursor to a fully developed, intense westward flow channel satisfying all of the criteria defining a PJ/SAID. A beam-swinging analysis showed that the westward drifts (poleward electric field) associated with the flow channel were very structured in time and space, but the smoothed velocities grew to ~ 800 ms -1 (47 mVm -1 ) during the 22-min substorm onset interval 09:56 to 10:18 UT. Maximum west-ward drifts of >1.3 km s -1 (>77 mVm -1 ) occurred during a ~ 5-min velocity spike, peaking at 10:40 UT during the expansion phase. The drifts decayed rapidly to ~ 300 ms -1 (18 mVm -1 ) during the 6-min recovery phase interval, 11:04 to 11:10 UT. Overall, the AWFC had a lifetime of 74 min, and was located near -65° L in the evening sector west of the Harang discontinuity. The large westward drifts were confined to a geographic zonal channel of longitudinal ex-tent >20° (>1.3 h magnetic local time), and latitudinal width ~2° L . Using a half-width of ~ 100 km in latitude, the peak electric potential was >7.7 kV. However, a transient velocity of >3.1 km s -1 with potential >18.4 kV was observed further poleward at the end of the recovery phase. Auroral oval boundaries determined using DMSP measurements suggest the main flow channel overlapped the equatorward boundary of the diffuse auroral oval. During the ~ 2-h interval following the flow channel, an ~ 3° L ... Article in Journal/Newspaper Macquarie Island Directory of Open Access Journals: DOAJ Articles Annales Geophysicae 21 4 893 913 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 M. L. Parkinson M. Pinnock H. Ye M. R. Hairston J. C. Devlin P. L. Dyson R. J. Morris P. Ponomarenko On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
A -190-nT negative bay in the geomagnetic X component measured at Macquarie Island ( -65° L ) showed that an ionospheric substorm occurred during 09:58 to 11:10 UT on 27 February 2000. Signatures of an auroral westward flow channel (AWFC) were observed nearly simultaneously in the backscatter power, LOS Doppler velocity, and Doppler spectral width measured using the Tasman International Geospace Environment Radar (TIGER), a Southern Hemisphere HF SuperDARN radar. Many of the characteristics of the AWFC were similar to those occurring during a polarisation jet (PJ), or subauroral ion drift (SAID) event, and suggest that it may have been a pre-cursor to a fully developed, intense westward flow channel satisfying all of the criteria defining a PJ/SAID. A beam-swinging analysis showed that the westward drifts (poleward electric field) associated with the flow channel were very structured in time and space, but the smoothed velocities grew to ~ 800 ms -1 (47 mVm -1 ) during the 22-min substorm onset interval 09:56 to 10:18 UT. Maximum west-ward drifts of >1.3 km s -1 (>77 mVm -1 ) occurred during a ~ 5-min velocity spike, peaking at 10:40 UT during the expansion phase. The drifts decayed rapidly to ~ 300 ms -1 (18 mVm -1 ) during the 6-min recovery phase interval, 11:04 to 11:10 UT. Overall, the AWFC had a lifetime of 74 min, and was located near -65° L in the evening sector west of the Harang discontinuity. The large westward drifts were confined to a geographic zonal channel of longitudinal ex-tent >20° (>1.3 h magnetic local time), and latitudinal width ~2° L . Using a half-width of ~ 100 km in latitude, the peak electric potential was >7.7 kV. However, a transient velocity of >3.1 km s -1 with potential >18.4 kV was observed further poleward at the end of the recovery phase. Auroral oval boundaries determined using DMSP measurements suggest the main flow channel overlapped the equatorward boundary of the diffuse auroral oval. During the ~ 2-h interval following the flow channel, an ~ 3° L ... |
format |
Article in Journal/Newspaper |
author |
M. L. Parkinson M. Pinnock H. Ye M. R. Hairston J. C. Devlin P. L. Dyson R. J. Morris P. Ponomarenko |
author_facet |
M. L. Parkinson M. Pinnock H. Ye M. R. Hairston J. C. Devlin P. L. Dyson R. J. Morris P. Ponomarenko |
author_sort |
M. L. Parkinson |
title |
On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
title_short |
On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
title_full |
On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
title_fullStr |
On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
title_full_unstemmed |
On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm |
title_sort |
on the lifetime and extent of an auroral westward flow channel (awfc) observed during a magnetospheric substorm |
publisher |
Copernicus Publications |
publishDate |
2003 |
url |
https://doi.org/10.5194/angeo-21-893-2003 https://doaj.org/article/f019c56fde674e6aade4cec5548025b1 |
genre |
Macquarie Island |
genre_facet |
Macquarie Island |
op_source |
Annales Geophysicae, Vol 21, Pp 893-913 (2003) |
op_relation |
https://www.ann-geophys.net/21/893/2003/angeo-21-893-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-893-2003 0992-7689 1432-0576 https://doaj.org/article/f019c56fde674e6aade4cec5548025b1 |
op_doi |
https://doi.org/10.5194/angeo-21-893-2003 |
container_title |
Annales Geophysicae |
container_volume |
21 |
container_issue |
4 |
container_start_page |
893 |
op_container_end_page |
913 |
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1766066371607658496 |