EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere
We report observations of a sequence of quiet-time Earthward bursty bulk flows (BBFs) measured by the Cluster spacecraft in the near-tail plasma sheet (XGSM ~ −12 to −14 R E ) in the evening sector, and by simultaneous high-resolution measurements in the northern conjugate ionosphere by the EISCAT r...
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ftdoajarticles:oai:doaj.org/article:d28bda7f21054811820446a829e111f2 2023-05-15T16:04:30+02:00 EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere T. Pitkänen A. T. Aikio O. Amm K. Kauristie H. Nilsson K. U. Kaila 2011-02-01T00:00:00Z https://doi.org/10.5194/angeo-29-299-2011 https://doaj.org/article/d28bda7f21054811820446a829e111f2 EN eng Copernicus Publications https://www.ann-geophys.net/29/299/2011/angeo-29-299-2011.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-29-299-2011 0992-7689 1432-0576 https://doaj.org/article/d28bda7f21054811820446a829e111f2 Annales Geophysicae, Vol 29, Pp 299-319 (2011) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2011 ftdoajarticles https://doi.org/10.5194/angeo-29-299-2011 2022-12-30T21:14:25Z We report observations of a sequence of quiet-time Earthward bursty bulk flows (BBFs) measured by the Cluster spacecraft in the near-tail plasma sheet (XGSM ~ −12 to −14 R E ) in the evening sector, and by simultaneous high-resolution measurements in the northern conjugate ionosphere by the EISCAT radars, a MIRACLE all-sky camera and magnetometers, as well as a meridian-scanning photometer (MSP) in the Scandinavian sector on 17 October 2005. The BBFs at Cluster show signatures that are consistent with the plasma "bubble" model (Chen and Wolf, 1993, 1999), e.g. deflection and compression of the ambient plasma in front of the Earthward moving bubble, magnetic signatures of a flow shear region, and the proper flows inside the bubble. In addition, clear signatures of tailward return flows around the edges of the bubble can be identified. The duskside return flows are associated with significant decrease in plasma density, giving support to the recent suggestion by Walsh et al. (2009) of formation of a depleted wake. However, the same feature is not seen for the dawnside return flows, but rather an increase in density. In the ionosphere, EISCAT and optical measurements show that each of the studied BBFs is associated with an auroral streamer that starts from the vicinity of the polar cap boundary, intrudes equatorward, brakes at 68–70° aacgm MLAT and drifts westward along the proton oval. Within the streamer itself and poleward of it, the ionospheric plasma flow has an equatorward component, which is the ionospheric manifestation of the Earthward BBF channel. A sharp velocity shear appears at the equatorward edge of a streamer. We suggest that each BBF creates a local velocity shear in the ionosphere, in which the plasma flow poleward of and inside the streamer is in the direction of the streamer and southeastward. A northwestward return flow is located on the equatorward side. The return flow is associated with decreased plasma densities both in the ionosphere and in the magnetosphere as measured by EISCAT and ... Article in Journal/Newspaper EISCAT Directory of Open Access Journals: DOAJ Articles Annales Geophysicae 29 2 299 319 |
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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 T. Pitkänen A. T. Aikio O. Amm K. Kauristie H. Nilsson K. U. Kaila EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
We report observations of a sequence of quiet-time Earthward bursty bulk flows (BBFs) measured by the Cluster spacecraft in the near-tail plasma sheet (XGSM ~ −12 to −14 R E ) in the evening sector, and by simultaneous high-resolution measurements in the northern conjugate ionosphere by the EISCAT radars, a MIRACLE all-sky camera and magnetometers, as well as a meridian-scanning photometer (MSP) in the Scandinavian sector on 17 October 2005. The BBFs at Cluster show signatures that are consistent with the plasma "bubble" model (Chen and Wolf, 1993, 1999), e.g. deflection and compression of the ambient plasma in front of the Earthward moving bubble, magnetic signatures of a flow shear region, and the proper flows inside the bubble. In addition, clear signatures of tailward return flows around the edges of the bubble can be identified. The duskside return flows are associated with significant decrease in plasma density, giving support to the recent suggestion by Walsh et al. (2009) of formation of a depleted wake. However, the same feature is not seen for the dawnside return flows, but rather an increase in density. In the ionosphere, EISCAT and optical measurements show that each of the studied BBFs is associated with an auroral streamer that starts from the vicinity of the polar cap boundary, intrudes equatorward, brakes at 68–70° aacgm MLAT and drifts westward along the proton oval. Within the streamer itself and poleward of it, the ionospheric plasma flow has an equatorward component, which is the ionospheric manifestation of the Earthward BBF channel. A sharp velocity shear appears at the equatorward edge of a streamer. We suggest that each BBF creates a local velocity shear in the ionosphere, in which the plasma flow poleward of and inside the streamer is in the direction of the streamer and southeastward. A northwestward return flow is located on the equatorward side. The return flow is associated with decreased plasma densities both in the ionosphere and in the magnetosphere as measured by EISCAT and ... |
format |
Article in Journal/Newspaper |
author |
T. Pitkänen A. T. Aikio O. Amm K. Kauristie H. Nilsson K. U. Kaila |
author_facet |
T. Pitkänen A. T. Aikio O. Amm K. Kauristie H. Nilsson K. U. Kaila |
author_sort |
T. Pitkänen |
title |
EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
title_short |
EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
title_full |
EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
title_fullStr |
EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
title_full_unstemmed |
EISCAT-Cluster observations of quiet-time near-Earth magnetotail fast flows and their signatures in the ionosphere |
title_sort |
eiscat-cluster observations of quiet-time near-earth magnetotail fast flows and their signatures in the ionosphere |
publisher |
Copernicus Publications |
publishDate |
2011 |
url |
https://doi.org/10.5194/angeo-29-299-2011 https://doaj.org/article/d28bda7f21054811820446a829e111f2 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Annales Geophysicae, Vol 29, Pp 299-319 (2011) |
op_relation |
https://www.ann-geophys.net/29/299/2011/angeo-29-299-2011.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-29-299-2011 0992-7689 1432-0576 https://doaj.org/article/d28bda7f21054811820446a829e111f2 |
op_doi |
https://doi.org/10.5194/angeo-29-299-2011 |
container_title |
Annales Geophysicae |
container_volume |
29 |
container_issue |
2 |
container_start_page |
299 |
op_container_end_page |
319 |
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1766400088499814400 |