Thermospheric density structures over the polar regions observed with CHAMP
International audience We report on the unexpected detection of considerable structure in high latitude thermospheric densities, as derived from an accelerometer onboard the CHAMP satellite. The width of the structures, which can either be maxima or minima, varies between a few hundred km and 2000 k...
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ftinsu:oai:HAL:hal-00317819v1 2024-04-14T08:11:04+00:00 Thermospheric density structures over the polar regions observed with CHAMP Schlegel, K. Lühr, H. St.-Maurice, J.-P. Crowley, G. Hackert, C. Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS) Max-Planck-Gesellschaft German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ) Institute of Space and Atmospheric Studies Saskatoon (ISAS) Department of Physics and Engineering Physics Saskatoon University of Saskatchewan Saskatoon (U of S)-University of Saskatchewan Saskatoon (U of S) Southwest Research Institute San Antonio (SwRI) 2005-07-28 https://hal.science/hal-00317819 https://hal.science/hal-00317819/document https://hal.science/hal-00317819/file/angeo-23-1659-2005.pdf en eng HAL CCSD European Geosciences Union hal-00317819 https://hal.science/hal-00317819 https://hal.science/hal-00317819/document https://hal.science/hal-00317819/file/angeo-23-1659-2005.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317819 Annales Geophysicae, 2005, 23 (5), pp.1659-1672 [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 2005 ftinsu 2024-03-21T17:18:05Z International audience We report on the unexpected detection of considerable structure in high latitude thermospheric densities, as derived from an accelerometer onboard the CHAMP satellite. The width of the structures, which can either be maxima or minima, varies between a few hundred km and 2000 km. The amplitudes of these density extrema can reach 50% of ambient. Maxima cluster around 75° (N and S), while minima are found closer to the poles. In a magnetic latitude-magnetic local time frame the maxima are found mainly around the cusp region. Overall, the observed structures somewhat resemble so-called density cells previously found in model calculations. However the models generate their cells around 140?300 km altitude and show little, if any remnant at 400 km or above. This has to be contrasted with the fact that the CHAMP observations were obtained near 430 km altitude. We have explored Joule heating as a possible mechanism for the generation of the structures, at least in density enhancement regions, using Hall currents measured on CHAMP and simultaneous incoherent scatter measurements with EISCAT. However, the electric fields were usually quite small during the period of observation, making the quest for an explanation for the structures all the more challenging. Keywords. Meteorology and atmospheric dynamics (Thermospheric dynamics) ? Magnetospheric physics (Polar cap phenomena) ? Atmospheric composition and structure (Pressure, density, and temperature) Article in Journal/Newspaper EISCAT Institut national des sciences de l'Univers: HAL-INSU |
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Open Polar |
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Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
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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 Schlegel, K. Lühr, H. St.-Maurice, J.-P. Crowley, G. Hackert, C. Thermospheric density structures over the polar regions observed with CHAMP |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience We report on the unexpected detection of considerable structure in high latitude thermospheric densities, as derived from an accelerometer onboard the CHAMP satellite. The width of the structures, which can either be maxima or minima, varies between a few hundred km and 2000 km. The amplitudes of these density extrema can reach 50% of ambient. Maxima cluster around 75° (N and S), while minima are found closer to the poles. In a magnetic latitude-magnetic local time frame the maxima are found mainly around the cusp region. Overall, the observed structures somewhat resemble so-called density cells previously found in model calculations. However the models generate their cells around 140?300 km altitude and show little, if any remnant at 400 km or above. This has to be contrasted with the fact that the CHAMP observations were obtained near 430 km altitude. We have explored Joule heating as a possible mechanism for the generation of the structures, at least in density enhancement regions, using Hall currents measured on CHAMP and simultaneous incoherent scatter measurements with EISCAT. However, the electric fields were usually quite small during the period of observation, making the quest for an explanation for the structures all the more challenging. Keywords. Meteorology and atmospheric dynamics (Thermospheric dynamics) ? Magnetospheric physics (Polar cap phenomena) ? Atmospheric composition and structure (Pressure, density, and temperature) |
author2 |
Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS) Max-Planck-Gesellschaft German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ) Institute of Space and Atmospheric Studies Saskatoon (ISAS) Department of Physics and Engineering Physics Saskatoon University of Saskatchewan Saskatoon (U of S)-University of Saskatchewan Saskatoon (U of S) Southwest Research Institute San Antonio (SwRI) |
format |
Article in Journal/Newspaper |
author |
Schlegel, K. Lühr, H. St.-Maurice, J.-P. Crowley, G. Hackert, C. |
author_facet |
Schlegel, K. Lühr, H. St.-Maurice, J.-P. Crowley, G. Hackert, C. |
author_sort |
Schlegel, K. |
title |
Thermospheric density structures over the polar regions observed with CHAMP |
title_short |
Thermospheric density structures over the polar regions observed with CHAMP |
title_full |
Thermospheric density structures over the polar regions observed with CHAMP |
title_fullStr |
Thermospheric density structures over the polar regions observed with CHAMP |
title_full_unstemmed |
Thermospheric density structures over the polar regions observed with CHAMP |
title_sort |
thermospheric density structures over the polar regions observed with champ |
publisher |
HAL CCSD |
publishDate |
2005 |
url |
https://hal.science/hal-00317819 https://hal.science/hal-00317819/document https://hal.science/hal-00317819/file/angeo-23-1659-2005.pdf |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317819 Annales Geophysicae, 2005, 23 (5), pp.1659-1672 |
op_relation |
hal-00317819 https://hal.science/hal-00317819 https://hal.science/hal-00317819/document https://hal.science/hal-00317819/file/angeo-23-1659-2005.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1796308729897943040 |