Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures
We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ( [ XGSM, YGSM, ZGSM ] ≈ [ 2, 7, 9 ] RE). The events take place during an interval of northward IMF, as seen in the data fr...
Published in: | Annales Geophysicae |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
European Geosciences Union (EGU), Copernicus Publications
2016
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Subjects: | |
Online Access: | http://www.ann-geophys.net/19/1613/2001/ http://hdl.handle.net/2381/37309 https://doi.org/10.5194/angeo-19-1613-2001 |
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ftleicester:oai:lra.le.ac.uk:2381/37309 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
topic |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology magnetospheric physics magnetopause cusp and boundary layers magnetosphere-ionosphere interactions solar wind-magnetosphere interactions FLUX-TRANSFER EVENTS INTERPLANETARY MAGNETIC-FIELD PARTICLE-PRECIPITATION CHARACTERISTICS CONVECTION ELECTRIC-FIELDS ACCELERATED FLOW EVENTS LOW-ALTITUDE SATELLITE DAYSIDE MAGNETOPAUSE ION PRECIPITATION UNEXPECTED FEATURES BIRKELAND CURRENTS |
spellingShingle |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology magnetospheric physics magnetopause cusp and boundary layers magnetosphere-ionosphere interactions solar wind-magnetosphere interactions FLUX-TRANSFER EVENTS INTERPLANETARY MAGNETIC-FIELD PARTICLE-PRECIPITATION CHARACTERISTICS CONVECTION ELECTRIC-FIELDS ACCELERATED FLOW EVENTS LOW-ALTITUDE SATELLITE DAYSIDE MAGNETOPAUSE ION PRECIPITATION UNEXPECTED FEATURES BIRKELAND CURRENTS Lockwood, M. Fazakerley, A. Opgenoorth, H. Moen, J. van Eyken, A. P. Dunlop, M. Bosqued, J. M. Lu, G. Cully, C. Eglitis, P. McCrea, I. W. Hapgood, M. A. Wild, M. N. Stamper, R. Denig, W. Taylor, M. Wild, J. A. Provan, G. Amm, O. Kauristie, K. Pulkkinen, T. Stromme, A. Prikryl, P. Pitout, F. Balogh, A. Reme, H. Behlke, R. Hansen, T. Greenwald, R. Frey, H. Morley, S. K. Alcayde, D. Blelly, P. L. Donovan, E. Engebretson, M. Lester, Mark Watermann, J. Marcucci, M. F. Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
topic_facet |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology magnetospheric physics magnetopause cusp and boundary layers magnetosphere-ionosphere interactions solar wind-magnetosphere interactions FLUX-TRANSFER EVENTS INTERPLANETARY MAGNETIC-FIELD PARTICLE-PRECIPITATION CHARACTERISTICS CONVECTION ELECTRIC-FIELDS ACCELERATED FLOW EVENTS LOW-ALTITUDE SATELLITE DAYSIDE MAGNETOPAUSE ION PRECIPITATION UNEXPECTED FEATURES BIRKELAND CURRENTS |
description |
We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ( [ XGSM, YGSM, ZGSM ] ≈ [ 2, 7, 9 ] RE). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a propagation delay of 75 min that is welldefined by two separate studies: (1) the magnetospheric variations prior to the northward turning (Lockwood et al., 2001, this issue) and (2) the field clock angle seen by Cluster after it had emerged into the magnetosheath (Opgenoorth et al., 2001, this issue). With an additional lag of 16.5 min, the transient LLBL events correlate well with swings of the IMF clock angle (in GSM) to near 90°. Most of this additional lag is explained by ground-based observations, which reveal signatures of transient reconnection in the pre-noon sector that then take 10–15 min to propagate eastward to 15 MLT, where they are observed by Cluster. The eastward phase speed of these signatures agrees very well with the motion deduced by the cross-correlation of the signatures seen on the four Cluster spacecraft. The evidence that these events are reconnection pulses includes: transient erosion of the noon 630 nm (cusp/cleft) aurora to lower latitudes; transient and travelling enhancements of the flow into the polar cap, imaged by the AMIE technique; and poleward-moving events moving into the polar cap, seen by the EISCAT Svalbard Radar (ESR). A pass of the DMSP-F15 satellite reveals that the open field lines near noon have been opened for some time: the more recently opened field lines were found closer to dusk where the flow transient and the poleward-moving event intersected the satellite pass. The events at Cluster have ion and electron characteristics predicted and observed by Lockwood and Hapgood (1998) for a Flux Transfer Event (FTE), with allowance for magnetospheric ion reflection at Alfvénic disturbances in the magnetopause reconnection layer. Like FTEs, the events are about 1 RE in their direction of motion and show a rise in the magnetic field strength, but unlike FTEs, in general, they show no pressure excess in their core and hence, no characteristic bipolar signature in the boundary-normal component. However, most of the events were observed when the magnetic field was southward, i.e. on the edge of the interior magnetic cusp, or when the field was parallel to the magnetic equatorial plane. Only when the satellite begins to emerge from the exterior boundary (when the field was northward), do the events start to show a pressure excess in their core and the consequent bipolar signature. We identify the events as the first observations of FTEs at middle altitudes. Peer-reviewed Publisher Version |
format |
Article in Journal/Newspaper |
author |
Lockwood, M. Fazakerley, A. Opgenoorth, H. Moen, J. van Eyken, A. P. Dunlop, M. Bosqued, J. M. Lu, G. Cully, C. Eglitis, P. McCrea, I. W. Hapgood, M. A. Wild, M. N. Stamper, R. Denig, W. Taylor, M. Wild, J. A. Provan, G. Amm, O. Kauristie, K. Pulkkinen, T. Stromme, A. Prikryl, P. Pitout, F. Balogh, A. Reme, H. Behlke, R. Hansen, T. Greenwald, R. Frey, H. Morley, S. K. Alcayde, D. Blelly, P. L. Donovan, E. Engebretson, M. Lester, Mark Watermann, J. Marcucci, M. F. |
author_facet |
Lockwood, M. Fazakerley, A. Opgenoorth, H. Moen, J. van Eyken, A. P. Dunlop, M. Bosqued, J. M. Lu, G. Cully, C. Eglitis, P. McCrea, I. W. Hapgood, M. A. Wild, M. N. Stamper, R. Denig, W. Taylor, M. Wild, J. A. Provan, G. Amm, O. Kauristie, K. Pulkkinen, T. Stromme, A. Prikryl, P. Pitout, F. Balogh, A. Reme, H. Behlke, R. Hansen, T. Greenwald, R. Frey, H. Morley, S. K. Alcayde, D. Blelly, P. L. Donovan, E. Engebretson, M. Lester, Mark Watermann, J. Marcucci, M. F. |
author_sort |
Lockwood, M. |
title |
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
title_short |
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
title_full |
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
title_fullStr |
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
title_full_unstemmed |
Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures |
title_sort |
coordinated cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward imf: relation to reconnection pulses and fte signatures |
publisher |
European Geosciences Union (EGU), Copernicus Publications |
publishDate |
2016 |
url |
http://www.ann-geophys.net/19/1613/2001/ http://hdl.handle.net/2381/37309 https://doi.org/10.5194/angeo-19-1613-2001 |
long_lat |
ENVELOPE(16.587,16.587,68.594,68.594) ENVELOPE(167.400,167.400,-84.150,-84.150) |
geographic |
Birkeland Lockwood Svalbard |
geographic_facet |
Birkeland Lockwood Svalbard |
genre |
EISCAT Svalbard |
genre_facet |
EISCAT Svalbard |
op_relation |
Annales Geophysicae, 2001, 19 (10-12), pp. 1613-1640 (28) 0992-7689 http://www.ann-geophys.net/19/1613/2001/ http://hdl.handle.net/2381/37309 doi:10.5194/angeo-19-1613-2001 1432-0576 |
op_rights |
Copyright © Author(s) 2001. This work is distributed under the Creative Commons Attribution 3.0 License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/angeo-19-1613-2001 |
container_title |
Annales Geophysicae |
container_volume |
19 |
container_issue |
10/12 |
container_start_page |
1613 |
op_container_end_page |
1640 |
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1766400491990810624 |
spelling |
ftleicester:oai:lra.le.ac.uk:2381/37309 2023-05-15T16:04:51+02:00 Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF: relation to reconnection pulses and FTE signatures Lockwood, M. Fazakerley, A. Opgenoorth, H. Moen, J. van Eyken, A. P. Dunlop, M. Bosqued, J. M. Lu, G. Cully, C. Eglitis, P. McCrea, I. W. Hapgood, M. A. Wild, M. N. Stamper, R. Denig, W. Taylor, M. Wild, J. A. Provan, G. Amm, O. Kauristie, K. Pulkkinen, T. Stromme, A. Prikryl, P. Pitout, F. Balogh, A. Reme, H. Behlke, R. Hansen, T. Greenwald, R. Frey, H. Morley, S. K. Alcayde, D. Blelly, P. L. Donovan, E. Engebretson, M. Lester, Mark Watermann, J. Marcucci, M. F. 2016-04-14T11:31:46Z http://www.ann-geophys.net/19/1613/2001/ http://hdl.handle.net/2381/37309 https://doi.org/10.5194/angeo-19-1613-2001 en eng European Geosciences Union (EGU), Copernicus Publications Annales Geophysicae, 2001, 19 (10-12), pp. 1613-1640 (28) 0992-7689 http://www.ann-geophys.net/19/1613/2001/ http://hdl.handle.net/2381/37309 doi:10.5194/angeo-19-1613-2001 1432-0576 Copyright © Author(s) 2001. This work is distributed under the Creative Commons Attribution 3.0 License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. CC-BY Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology magnetospheric physics magnetopause cusp and boundary layers magnetosphere-ionosphere interactions solar wind-magnetosphere interactions FLUX-TRANSFER EVENTS INTERPLANETARY MAGNETIC-FIELD PARTICLE-PRECIPITATION CHARACTERISTICS CONVECTION ELECTRIC-FIELDS ACCELERATED FLOW EVENTS LOW-ALTITUDE SATELLITE DAYSIDE MAGNETOPAUSE ION PRECIPITATION UNEXPECTED FEATURES BIRKELAND CURRENTS Journal Article Review;Journal 2016 ftleicester https://doi.org/10.5194/angeo-19-1613-2001 2019-03-22T20:21:24Z We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ( [ XGSM, YGSM, ZGSM ] ≈ [ 2, 7, 9 ] RE). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a propagation delay of 75 min that is welldefined by two separate studies: (1) the magnetospheric variations prior to the northward turning (Lockwood et al., 2001, this issue) and (2) the field clock angle seen by Cluster after it had emerged into the magnetosheath (Opgenoorth et al., 2001, this issue). With an additional lag of 16.5 min, the transient LLBL events correlate well with swings of the IMF clock angle (in GSM) to near 90°. Most of this additional lag is explained by ground-based observations, which reveal signatures of transient reconnection in the pre-noon sector that then take 10–15 min to propagate eastward to 15 MLT, where they are observed by Cluster. The eastward phase speed of these signatures agrees very well with the motion deduced by the cross-correlation of the signatures seen on the four Cluster spacecraft. The evidence that these events are reconnection pulses includes: transient erosion of the noon 630 nm (cusp/cleft) aurora to lower latitudes; transient and travelling enhancements of the flow into the polar cap, imaged by the AMIE technique; and poleward-moving events moving into the polar cap, seen by the EISCAT Svalbard Radar (ESR). A pass of the DMSP-F15 satellite reveals that the open field lines near noon have been opened for some time: the more recently opened field lines were found closer to dusk where the flow transient and the poleward-moving event intersected the satellite pass. The events at Cluster have ion and electron characteristics predicted and observed by Lockwood and Hapgood (1998) for a Flux Transfer Event (FTE), with allowance for magnetospheric ion reflection at Alfvénic disturbances in the magnetopause reconnection layer. Like FTEs, the events are about 1 RE in their direction of motion and show a rise in the magnetic field strength, but unlike FTEs, in general, they show no pressure excess in their core and hence, no characteristic bipolar signature in the boundary-normal component. However, most of the events were observed when the magnetic field was southward, i.e. on the edge of the interior magnetic cusp, or when the field was parallel to the magnetic equatorial plane. Only when the satellite begins to emerge from the exterior boundary (when the field was northward), do the events start to show a pressure excess in their core and the consequent bipolar signature. We identify the events as the first observations of FTEs at middle altitudes. Peer-reviewed Publisher Version Article in Journal/Newspaper EISCAT Svalbard University of Leicester: Leicester Research Archive (LRA) Birkeland ENVELOPE(16.587,16.587,68.594,68.594) Lockwood ENVELOPE(167.400,167.400,-84.150,-84.150) Svalbard Annales Geophysicae 19 10/12 1613 1640 |