Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp
International audience In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finlan...
Main Authors: | , , , , , |
---|---|
Other Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2004
|
Subjects: | |
Online Access: | https://hal.science/hal-00317234 https://hal.science/hal-00317234/document https://hal.science/hal-00317234/file/angeo-22-511-2004.pdf |
id |
ftccsdartic:oai:HAL:hal-00317234v1 |
---|---|
record_format |
openpolar |
spelling |
ftccsdartic:oai:HAL:hal-00317234v1 2023-11-12T04:27:04+01:00 Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp Oksavik, K. Søraas, F. Moen, J. Pfaff, R. Davies, J. A. Lester, M. Department of Physics Okayama University NASA Goddard Space Flight Center (GSFC) University of Leicester 2004-01-01 https://hal.science/hal-00317234 https://hal.science/hal-00317234/document https://hal.science/hal-00317234/file/angeo-22-511-2004.pdf en eng HAL CCSD European Geosciences Union hal-00317234 https://hal.science/hal-00317234 https://hal.science/hal-00317234/document https://hal.science/hal-00317234/file/angeo-22-511-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317234 Annales Geophysicae, 2004, 22 (2), pp.511-525 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2004 ftccsdartic 2023-10-21T23:07:35Z International audience In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps. Key words. Ionosphere (electric fields and currents). Magnetosphere physics (magnetopause, cusp, and boundary layers; auroral phenomena) Article in Journal/Newspaper Svalbard Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Svalbard |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Oksavik, K. Søraas, F. Moen, J. Pfaff, R. Davies, J. A. Lester, M. Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps. Key words. Ionosphere (electric fields and currents). Magnetosphere physics (magnetopause, cusp, and boundary layers; auroral phenomena) |
author2 |
Department of Physics Okayama University NASA Goddard Space Flight Center (GSFC) University of Leicester |
format |
Article in Journal/Newspaper |
author |
Oksavik, K. Søraas, F. Moen, J. Pfaff, R. Davies, J. A. Lester, M. |
author_facet |
Oksavik, K. Søraas, F. Moen, J. Pfaff, R. Davies, J. A. Lester, M. |
author_sort |
Oksavik, K. |
title |
Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
title_short |
Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
title_full |
Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
title_fullStr |
Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
title_full_unstemmed |
Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp |
title_sort |
simultaneous optical, cutlass hf radar, and fast spacecraft observations: signatures of boundary layer processes in the cusp |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00317234 https://hal.science/hal-00317234/document https://hal.science/hal-00317234/file/angeo-22-511-2004.pdf |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
Svalbard |
genre_facet |
Svalbard |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317234 Annales Geophysicae, 2004, 22 (2), pp.511-525 |
op_relation |
hal-00317234 https://hal.science/hal-00317234 https://hal.science/hal-00317234/document https://hal.science/hal-00317234/file/angeo-22-511-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782340811095015424 |