Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling
Ground-based observations of dayside auroral forms and magnetic perturbations in the arctic sectors of Svalbard and Greenland, in combination with the high-resolution measurements of ionospheric ion drift and temperature by the EISCAT radar, are used to study temporal/spatial structures of cusp-type...
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ftoslouniv:oai:www.duo.uio.no:10852/47927 2023-05-15T15:19:20+02:00 Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling Sandholt, P. E Moen, J. Stauning, P. Holtet, J. A Cowley, S. W H Lockwood, M. Løvhaug, U. P Hansen, T. Egeland, A. 2014 http://hdl.handle.net/10852/47927 http://urn.nb.no/URN:NBN:no-51953 https://doi.org/10.1186/BF03352161 eng eng http://urn.nb.no/URN:NBN:no-51953 http://hdl.handle.net/10852/47927 Earth, Planets and Space 50 8 663 682 http://dx.doi.org/10.1186/BF03352161 URN:NBN:no-51953 Fulltext https://www.duo.uio.no/bitstream/handle/10852/47927/1/40623_2014_Article_BF03352161.pdf The Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan Journal article Tidsskriftartikkel Peer reviewed PublishedVersion 2014 ftoslouniv https://doi.org/10.1186/BF03352161 2020-06-21T08:49:13Z Ground-based observations of dayside auroral forms and magnetic perturbations in the arctic sectors of Svalbard and Greenland, in combination with the high-resolution measurements of ionospheric ion drift and temperature by the EISCAT radar, are used to study temporal/spatial structures of cusp-type auroral forms in relation to convection. Large-scale patterns of equivalent convection in the dayside polar ionosphere are derived from the magnetic observations in Greenland and Svalbard. This information is used to estimate the ionospheric convection pattern in the vicinity of the cusp/cleft aurora. The reported observations, covering the period 0700–1130 UT, on January 11, 1993, are separated into four intervals according to the observed characteristics of the aurora and ionospheric convection. The morphology and intensity of the aurora are very different in quiet and disturbed intervals. A latitudinally narrow zone of intense and dynamical 630.0 nm emission equatorward of 75° MLAT, was observed during periods of enhanced antisunward convection in the cusp region. This (type 1 cusp aurora) is considered to be the signature of plasma entry via magnetopause reconnection at low magnetopause latitudes, i.e. the low-latitude boundary layer (LLBL). Another zone of weak 630.0 nm emission (type 2 cusp aurora) was observed to extend up to high latitudes (∼79° MLAT) during relatively quiet magnetic conditions, when indications of reverse (sunward) convection was observed in the dayside polar cap. This is postulated to be a signature of merging between a northward directed IMF (BZ > 0) and the geomagnetic field poleward of the cusp. The coexistence of type 1 and 2 auroras was observed under intermediate circumstances. The optical observations from Svalbard and Greenland were also used to determine the temporal and spatial evolution of type 1 auroral forms, i.e. poleward-moving auroral events occurring in the vicinity of a rotational convection reversal in the early post-noon sector. Each event appeared as a local brightening at the equatorward boundary of the pre-existing type 1 cusp aurora, followed by poleward and eastward expansions of luminosity. The auroral events were associated with poleward-moving surges of enhanced ionospheric convection and F-layer ion temperature as observed by the EISCAT radar in Tromsø. The EISCAT ion flow data in combination with the auroral observations show strong evidence for plasma flow across the open/closed field line boundary. Published Open Access with SpringerOpen. Article in Journal/Newspaper Arctic EISCAT Greenland Svalbard Tromsø Universitet i Oslo: Digitale utgivelser ved UiO (DUO) Arctic Greenland Svalbard Tromsø Earth, Planets and Space 50 8 663 682 |
institution |
Open Polar |
collection |
Universitet i Oslo: Digitale utgivelser ved UiO (DUO) |
op_collection_id |
ftoslouniv |
language |
English |
description |
Ground-based observations of dayside auroral forms and magnetic perturbations in the arctic sectors of Svalbard and Greenland, in combination with the high-resolution measurements of ionospheric ion drift and temperature by the EISCAT radar, are used to study temporal/spatial structures of cusp-type auroral forms in relation to convection. Large-scale patterns of equivalent convection in the dayside polar ionosphere are derived from the magnetic observations in Greenland and Svalbard. This information is used to estimate the ionospheric convection pattern in the vicinity of the cusp/cleft aurora. The reported observations, covering the period 0700–1130 UT, on January 11, 1993, are separated into four intervals according to the observed characteristics of the aurora and ionospheric convection. The morphology and intensity of the aurora are very different in quiet and disturbed intervals. A latitudinally narrow zone of intense and dynamical 630.0 nm emission equatorward of 75° MLAT, was observed during periods of enhanced antisunward convection in the cusp region. This (type 1 cusp aurora) is considered to be the signature of plasma entry via magnetopause reconnection at low magnetopause latitudes, i.e. the low-latitude boundary layer (LLBL). Another zone of weak 630.0 nm emission (type 2 cusp aurora) was observed to extend up to high latitudes (∼79° MLAT) during relatively quiet magnetic conditions, when indications of reverse (sunward) convection was observed in the dayside polar cap. This is postulated to be a signature of merging between a northward directed IMF (BZ > 0) and the geomagnetic field poleward of the cusp. The coexistence of type 1 and 2 auroras was observed under intermediate circumstances. The optical observations from Svalbard and Greenland were also used to determine the temporal and spatial evolution of type 1 auroral forms, i.e. poleward-moving auroral events occurring in the vicinity of a rotational convection reversal in the early post-noon sector. Each event appeared as a local brightening at the equatorward boundary of the pre-existing type 1 cusp aurora, followed by poleward and eastward expansions of luminosity. The auroral events were associated with poleward-moving surges of enhanced ionospheric convection and F-layer ion temperature as observed by the EISCAT radar in Tromsø. The EISCAT ion flow data in combination with the auroral observations show strong evidence for plasma flow across the open/closed field line boundary. Published Open Access with SpringerOpen. |
format |
Article in Journal/Newspaper |
author |
Sandholt, P. E Moen, J. Stauning, P. Holtet, J. A Cowley, S. W H Lockwood, M. Løvhaug, U. P Hansen, T. Egeland, A. |
spellingShingle |
Sandholt, P. E Moen, J. Stauning, P. Holtet, J. A Cowley, S. W H Lockwood, M. Løvhaug, U. P Hansen, T. Egeland, A. Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
author_facet |
Sandholt, P. E Moen, J. Stauning, P. Holtet, J. A Cowley, S. W H Lockwood, M. Løvhaug, U. P Hansen, T. Egeland, A. |
author_sort |
Sandholt, P. E |
title |
Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
title_short |
Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
title_full |
Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
title_fullStr |
Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
title_full_unstemmed |
Temporal and spatial variability of auroral forms in the 10–14 MLT sector: Relationship to plasma convection and solar wind-magnetosphere coupling |
title_sort |
temporal and spatial variability of auroral forms in the 10–14 mlt sector: relationship to plasma convection and solar wind-magnetosphere coupling |
publishDate |
2014 |
url |
http://hdl.handle.net/10852/47927 http://urn.nb.no/URN:NBN:no-51953 https://doi.org/10.1186/BF03352161 |
geographic |
Arctic Greenland Svalbard Tromsø |
geographic_facet |
Arctic Greenland Svalbard Tromsø |
genre |
Arctic EISCAT Greenland Svalbard Tromsø |
genre_facet |
Arctic EISCAT Greenland Svalbard Tromsø |
op_relation |
http://urn.nb.no/URN:NBN:no-51953 http://hdl.handle.net/10852/47927 Earth, Planets and Space 50 8 663 682 http://dx.doi.org/10.1186/BF03352161 URN:NBN:no-51953 Fulltext https://www.duo.uio.no/bitstream/handle/10852/47927/1/40623_2014_Article_BF03352161.pdf |
op_rights |
The Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan |
op_doi |
https://doi.org/10.1186/BF03352161 |
container_title |
Earth, Planets and Space |
container_volume |
50 |
container_issue |
8 |
container_start_page |
663 |
op_container_end_page |
682 |
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1766349509696159744 |