ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes
We report observations of the cusp/cleft ionosphere made on December 16th 1998 by the EISCAT (European incoherent scatter) VHF radar at Tromso and the EISCAT Svalbard radar (ESR). We compare them with observations of the dayside auroral luminosity, as seen by meridian scanning photometers at Ny Ales...
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2000
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Online Access: | https://centaur.reading.ac.uk/38733/ https://centaur.reading.ac.uk/38733/1/187_McCreaetal_AG_1009.pdf https://doi.org/10.1007/s00585-000-1009-7 |
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ftunivreading:oai:centaur.reading.ac.uk:38733 2024-06-23T07:52:27+00:00 ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes McCrea, I. W. Lockwood, Mike Moen, J. Pitout, F. Eglitis, P. Aylward, A. D. Cerisier, J.-C. Thorolfssen, A. Milan, S. E. 2000 text https://centaur.reading.ac.uk/38733/ https://centaur.reading.ac.uk/38733/1/187_McCreaetal_AG_1009.pdf https://doi.org/10.1007/s00585-000-1009-7 en eng Copernicus Publications https://centaur.reading.ac.uk/38733/1/187_McCreaetal_AG_1009.pdf McCrea, I. W., Lockwood, M. <https://centaur.reading.ac.uk/view/creators/90001127.html> orcid:0000-0002-7397-2172 , Moen, J., Pitout, F., Eglitis, P., Aylward, A. D., Cerisier, J.-C., Thorolfssen, A. and Milan, S. E. (2000) ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes. Annales Geophysicae, 18 (9). pp. 1009-1026. ISSN 0992-7689 doi: https://doi.org/10.1007/s00585-000-1009-7 <https://doi.org/10.1007/s00585-000-1009-7> cc_by Article PeerReviewed 2000 ftunivreading https://doi.org/10.1007/s00585-000-1009-7 2024-06-11T15:02:59Z We report observations of the cusp/cleft ionosphere made on December 16th 1998 by the EISCAT (European incoherent scatter) VHF radar at Tromso and the EISCAT Svalbard radar (ESR). We compare them with observations of the dayside auroral luminosity, as seen by meridian scanning photometers at Ny Alesund and of HF radar backscatter, as observed by the CUTLASS radar. We study the response to an interval of about one hour when the interplanetary magnetic field (IMF), monitored by the WIND and ACE spacecraft, was southward. The cusp/cleft aurora is shown to correspond to a spatially extended region of elevated electron temperatures in the VHF radar data. Initial conditions were characterised by a northward-directed IMF and cusp/cleft aurora poleward of the ESR. A strong southward turning then occurred, causing an equatorward motion of the cusp/cleft aurora. Within the equatorward expanding, southward-IMF cusp/cleft, the ESR observed structured and elevated plasma densities and ion and electron temperatures. Cleft ion fountain upflows were seen in association with elevated ion temperatures and rapid eastward convection, consistent with the magnetic curvature force on newly opened held lines for the observed negative IMF B-y. Subsequently, the ESR beam remained immediately poleward of the main cusp/cleft and a sequence of poleward-moving auroral transients passed over it. After the last of these, the ESR was in the polar cap and the radar observations were characterised by extremely low ionospheric densities and downward field-aligned flows. The IMF then turned northward again and the auroral oval contracted such that the ESR moved back into the cusp/cleft region. For the poleward-retreating northward-IMF cusp/cleft, the convection flows were slower, upflows were weaker and the electron density and temperature enhancements were less structured. Following the northward turning, the bands of high electron temperature and cusp/cleft aurora bifurcated, consistent with both subsolar and lobe reconnection taking place ... Article in Journal/Newspaper EISCAT Svalbard Tromso Tromso CentAUR: Central Archive at the University of Reading Svalbard Tromso ENVELOPE(16.546,16.546,68.801,68.801) Annales Geophysicae 18 9 1009 1026 |
institution |
Open Polar |
collection |
CentAUR: Central Archive at the University of Reading |
op_collection_id |
ftunivreading |
language |
English |
description |
We report observations of the cusp/cleft ionosphere made on December 16th 1998 by the EISCAT (European incoherent scatter) VHF radar at Tromso and the EISCAT Svalbard radar (ESR). We compare them with observations of the dayside auroral luminosity, as seen by meridian scanning photometers at Ny Alesund and of HF radar backscatter, as observed by the CUTLASS radar. We study the response to an interval of about one hour when the interplanetary magnetic field (IMF), monitored by the WIND and ACE spacecraft, was southward. The cusp/cleft aurora is shown to correspond to a spatially extended region of elevated electron temperatures in the VHF radar data. Initial conditions were characterised by a northward-directed IMF and cusp/cleft aurora poleward of the ESR. A strong southward turning then occurred, causing an equatorward motion of the cusp/cleft aurora. Within the equatorward expanding, southward-IMF cusp/cleft, the ESR observed structured and elevated plasma densities and ion and electron temperatures. Cleft ion fountain upflows were seen in association with elevated ion temperatures and rapid eastward convection, consistent with the magnetic curvature force on newly opened held lines for the observed negative IMF B-y. Subsequently, the ESR beam remained immediately poleward of the main cusp/cleft and a sequence of poleward-moving auroral transients passed over it. After the last of these, the ESR was in the polar cap and the radar observations were characterised by extremely low ionospheric densities and downward field-aligned flows. The IMF then turned northward again and the auroral oval contracted such that the ESR moved back into the cusp/cleft region. For the poleward-retreating northward-IMF cusp/cleft, the convection flows were slower, upflows were weaker and the electron density and temperature enhancements were less structured. Following the northward turning, the bands of high electron temperature and cusp/cleft aurora bifurcated, consistent with both subsolar and lobe reconnection taking place ... |
format |
Article in Journal/Newspaper |
author |
McCrea, I. W. Lockwood, Mike Moen, J. Pitout, F. Eglitis, P. Aylward, A. D. Cerisier, J.-C. Thorolfssen, A. Milan, S. E. |
spellingShingle |
McCrea, I. W. Lockwood, Mike Moen, J. Pitout, F. Eglitis, P. Aylward, A. D. Cerisier, J.-C. Thorolfssen, A. Milan, S. E. ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
author_facet |
McCrea, I. W. Lockwood, Mike Moen, J. Pitout, F. Eglitis, P. Aylward, A. D. Cerisier, J.-C. Thorolfssen, A. Milan, S. E. |
author_sort |
McCrea, I. W. |
title |
ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
title_short |
ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
title_full |
ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
title_fullStr |
ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
title_full_unstemmed |
ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes |
title_sort |
esr and eiscat observations of the response of the cusp and cleft to imf orientation changes |
publisher |
Copernicus Publications |
publishDate |
2000 |
url |
https://centaur.reading.ac.uk/38733/ https://centaur.reading.ac.uk/38733/1/187_McCreaetal_AG_1009.pdf https://doi.org/10.1007/s00585-000-1009-7 |
long_lat |
ENVELOPE(16.546,16.546,68.801,68.801) |
geographic |
Svalbard Tromso |
geographic_facet |
Svalbard Tromso |
genre |
EISCAT Svalbard Tromso Tromso |
genre_facet |
EISCAT Svalbard Tromso Tromso |
op_relation |
https://centaur.reading.ac.uk/38733/1/187_McCreaetal_AG_1009.pdf McCrea, I. W., Lockwood, M. <https://centaur.reading.ac.uk/view/creators/90001127.html> orcid:0000-0002-7397-2172 , Moen, J., Pitout, F., Eglitis, P., Aylward, A. D., Cerisier, J.-C., Thorolfssen, A. and Milan, S. E. (2000) ESR and EISCAT observations of the response of the cusp and cleft to IMF orientation changes. Annales Geophysicae, 18 (9). pp. 1009-1026. ISSN 0992-7689 doi: https://doi.org/10.1007/s00585-000-1009-7 <https://doi.org/10.1007/s00585-000-1009-7> |
op_rights |
cc_by |
op_doi |
https://doi.org/10.1007/s00585-000-1009-7 |
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Annales Geophysicae |
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18 |
container_issue |
9 |
container_start_page |
1009 |
op_container_end_page |
1026 |
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1802643757963673600 |