Ion flows and heating at a contracting polar-cap boundary
Data recorded by the POLAR experiment run on the EISCAT radar during the international GISMOS campaign of 3–5 June 1987 are studied in detail. The polar-cap boundary, as denned by an almost shear East-West convection reversal, was observed to jump southward across the EISCAT field of view in two ste...
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1988
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Online Access: | https://centaur.reading.ac.uk/38891/ https://doi.org/10.1016/0032-0633(88)90076-1 |
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ftunivreading:oai:centaur.reading.ac.uk:38891 2024-06-23T07:52:27+00:00 Ion flows and heating at a contracting polar-cap boundary Lockwood, Mike Cowley, S.W.H. Todd, H. Willis, D.M. Clauer, C.R. 1988 https://centaur.reading.ac.uk/38891/ https://doi.org/10.1016/0032-0633(88)90076-1 unknown Elsevier Lockwood, M. <https://centaur.reading.ac.uk/view/creators/90001127.html> orcid:0000-0002-7397-2172 , Cowley, S.W.H., Todd, H., Willis, D.M. and Clauer, C.R. (1988) Ion flows and heating at a contracting polar-cap boundary. Planetary and Space Science, 36 (11). pp. 1229-1253. ISSN 0032-0633 doi: https://doi.org/10.1016/0032-0633(88)90076-1 <https://doi.org/10.1016/0032-0633(88)90076-1> Article PeerReviewed 1988 ftunivreading https://doi.org/10.1016/0032-0633(88)90076-1 2024-06-11T15:02:59Z Data recorded by the POLAR experiment run on the EISCAT radar during the international GISMOS campaign of 3–5 June 1987 are studied in detail. The polar-cap boundary, as denned by an almost shear East-West convection reversal, was observed to jump southward across the EISCAT field of view in two steps at 02:00 and 03:00 Magnetic Local Time and subsequently to contract back between 04:00 and 07:00 M.L.T. An annulus of enhanced ion temperature and non-thermal plasma was observed immediately equatorward of the contracting boundary due to the lag in the response of the neutral-wind pattern to the change in ion flows. The ion flow at the boundary is shown to be relatively smooth at 15 s resolution and directed northward, with velocities which exceed that of the boundary itself. The effect of velocity shears on the beamswinging technique used to derive the ion flows is analyzed in detail and it is shown that, for certain orientations of the cap boundary, spurious flows into the cap can be generated. However, these are much smaller than the observed flows into the polar cap and cannot explain the potential difference across the observed segment of the cap boundary (extending over 2 h of M.L.T.) which is roughly 7 kV. Similarly, an observed slowing of the zonal flow near the boundary cannot be explained as an error introduced by the use of the beamswinging technique. The results could be interpreted as being due to reconnection occurring on the dawn flank of the magnetopause (mapping to the polar cap at 04:30 06:30 M.L.T.). However, they are more consistent with recent observations of slow anti-sunward flow of closed field lines on the flanks of the geomagnetic tail, which appears to be generated by some form of “viscous” coupling to the magnetosheath plasma. Article in Journal/Newspaper EISCAT CentAUR: Central Archive at the University of Reading Planetary and Space Science 36 11 1229 1253 |
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Open Polar |
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CentAUR: Central Archive at the University of Reading |
op_collection_id |
ftunivreading |
language |
unknown |
description |
Data recorded by the POLAR experiment run on the EISCAT radar during the international GISMOS campaign of 3–5 June 1987 are studied in detail. The polar-cap boundary, as denned by an almost shear East-West convection reversal, was observed to jump southward across the EISCAT field of view in two steps at 02:00 and 03:00 Magnetic Local Time and subsequently to contract back between 04:00 and 07:00 M.L.T. An annulus of enhanced ion temperature and non-thermal plasma was observed immediately equatorward of the contracting boundary due to the lag in the response of the neutral-wind pattern to the change in ion flows. The ion flow at the boundary is shown to be relatively smooth at 15 s resolution and directed northward, with velocities which exceed that of the boundary itself. The effect of velocity shears on the beamswinging technique used to derive the ion flows is analyzed in detail and it is shown that, for certain orientations of the cap boundary, spurious flows into the cap can be generated. However, these are much smaller than the observed flows into the polar cap and cannot explain the potential difference across the observed segment of the cap boundary (extending over 2 h of M.L.T.) which is roughly 7 kV. Similarly, an observed slowing of the zonal flow near the boundary cannot be explained as an error introduced by the use of the beamswinging technique. The results could be interpreted as being due to reconnection occurring on the dawn flank of the magnetopause (mapping to the polar cap at 04:30 06:30 M.L.T.). However, they are more consistent with recent observations of slow anti-sunward flow of closed field lines on the flanks of the geomagnetic tail, which appears to be generated by some form of “viscous” coupling to the magnetosheath plasma. |
format |
Article in Journal/Newspaper |
author |
Lockwood, Mike Cowley, S.W.H. Todd, H. Willis, D.M. Clauer, C.R. |
spellingShingle |
Lockwood, Mike Cowley, S.W.H. Todd, H. Willis, D.M. Clauer, C.R. Ion flows and heating at a contracting polar-cap boundary |
author_facet |
Lockwood, Mike Cowley, S.W.H. Todd, H. Willis, D.M. Clauer, C.R. |
author_sort |
Lockwood, Mike |
title |
Ion flows and heating at a contracting polar-cap boundary |
title_short |
Ion flows and heating at a contracting polar-cap boundary |
title_full |
Ion flows and heating at a contracting polar-cap boundary |
title_fullStr |
Ion flows and heating at a contracting polar-cap boundary |
title_full_unstemmed |
Ion flows and heating at a contracting polar-cap boundary |
title_sort |
ion flows and heating at a contracting polar-cap boundary |
publisher |
Elsevier |
publishDate |
1988 |
url |
https://centaur.reading.ac.uk/38891/ https://doi.org/10.1016/0032-0633(88)90076-1 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
Lockwood, M. <https://centaur.reading.ac.uk/view/creators/90001127.html> orcid:0000-0002-7397-2172 , Cowley, S.W.H., Todd, H., Willis, D.M. and Clauer, C.R. (1988) Ion flows and heating at a contracting polar-cap boundary. Planetary and Space Science, 36 (11). pp. 1229-1253. ISSN 0032-0633 doi: https://doi.org/10.1016/0032-0633(88)90076-1 <https://doi.org/10.1016/0032-0633(88)90076-1> |
op_doi |
https://doi.org/10.1016/0032-0633(88)90076-1 |
container_title |
Planetary and Space Science |
container_volume |
36 |
container_issue |
11 |
container_start_page |
1229 |
op_container_end_page |
1253 |
_version_ |
1802643760767565824 |