Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations
During a southward orientation of the interplanetary magnetic field (IMF), patches are often observed moving antisunward across the polar cap. In saying “patches” we refer to structures in which the F region electron densities are enhanced relative to lower background levels; we do not in this paper...
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ftutahsudc:oai:digitalcommons.usu.edu:physics_facpub-1177 2023-05-15T16:30:26+02:00 Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations Bowline, M. D. Sojka, Jan Josef Schunk, Robert W. 1996-01-01T08:00:00Z application/pdf https://digitalcommons.usu.edu/physics_facpub/178 https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1177&context=physics_facpub unknown Hosted by Utah State University Libraries https://digitalcommons.usu.edu/physics_facpub/178 https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1177&context=physics_facpub Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact the Institutional Repository Librarian at digitalcommons@usu.edu. PDM All Physics Faculty Publications theoretical patch climatology polar cap patch observations Physics text 1996 ftutahsudc 2022-03-07T22:26:02Z During a southward orientation of the interplanetary magnetic field (IMF), patches are often observed moving antisunward across the polar cap. In saying “patches” we refer to structures in which the F region electron densities are enhanced relative to lower background levels; we do not in this paper consider patches which are observed optically (see J. J. Sojka et al., Ambiguity in identificiation of polar cap F region patches, submitted to the Journal of Atmospheric and Terrestrial Physics, 1995). The patches can be modeled by a process which involves the “chopping up” of the tongue of ionization (TOI) [Sojka et al., 1993a]. Various mechanisms for chopping the TOI have been suggested; our preferred method is to introduce temporal changes in the convection electric field pattern. In any case the present study is quite independent of any particular mechanism, so long as the TOI is considered to be the source of the patches. In this study we have used the Utah State University Time-Dependent Ionospheric Model (TDIM) to model the TOI for various IMF By orientations. In our simulations the location of the TOI in the polar cap is mainly determined by the IMF B y component, and hence the patch locations are also expected to be B y dependent. This suggests that a polar ground-based instrument may not see patches even when they are present in the polar ionosphere. This is because the typical field of view of a ground-based instrument, such as an all-sky camera, covers less than 10% of the polar region. The TDIM simulation results were used to predict the B y dependence of patches that different ground-based sites would observe. Eureka (Canada) at the magnetic pole is predicted not to observe patches for southward IMF conditions if the B y component is strongly negative. Sondrestrom (Greenland) and NyAlesund (Svalbard), although at similar cusp latitudes, are expected to see quite different diurnal responses to patches. At Sondrestrom, patches are seen at noon in winter; both sites should see them in the premidnight sector. These model predictions are the “groundwork” for detailed patch observation-model comparisons at all three sites. Text Greenland Svalbard Utah State University: DigitalCommons@USU Canada Eureka ENVELOPE(-85.940,-85.940,79.990,79.990) Greenland Svalbard |
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Open Polar |
collection |
Utah State University: DigitalCommons@USU |
op_collection_id |
ftutahsudc |
language |
unknown |
topic |
theoretical patch climatology polar cap patch observations Physics |
spellingShingle |
theoretical patch climatology polar cap patch observations Physics Bowline, M. D. Sojka, Jan Josef Schunk, Robert W. Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
topic_facet |
theoretical patch climatology polar cap patch observations Physics |
description |
During a southward orientation of the interplanetary magnetic field (IMF), patches are often observed moving antisunward across the polar cap. In saying “patches” we refer to structures in which the F region electron densities are enhanced relative to lower background levels; we do not in this paper consider patches which are observed optically (see J. J. Sojka et al., Ambiguity in identificiation of polar cap F region patches, submitted to the Journal of Atmospheric and Terrestrial Physics, 1995). The patches can be modeled by a process which involves the “chopping up” of the tongue of ionization (TOI) [Sojka et al., 1993a]. Various mechanisms for chopping the TOI have been suggested; our preferred method is to introduce temporal changes in the convection electric field pattern. In any case the present study is quite independent of any particular mechanism, so long as the TOI is considered to be the source of the patches. In this study we have used the Utah State University Time-Dependent Ionospheric Model (TDIM) to model the TOI for various IMF By orientations. In our simulations the location of the TOI in the polar cap is mainly determined by the IMF B y component, and hence the patch locations are also expected to be B y dependent. This suggests that a polar ground-based instrument may not see patches even when they are present in the polar ionosphere. This is because the typical field of view of a ground-based instrument, such as an all-sky camera, covers less than 10% of the polar region. The TDIM simulation results were used to predict the B y dependence of patches that different ground-based sites would observe. Eureka (Canada) at the magnetic pole is predicted not to observe patches for southward IMF conditions if the B y component is strongly negative. Sondrestrom (Greenland) and NyAlesund (Svalbard), although at similar cusp latitudes, are expected to see quite different diurnal responses to patches. At Sondrestrom, patches are seen at noon in winter; both sites should see them in the premidnight sector. These model predictions are the “groundwork” for detailed patch observation-model comparisons at all three sites. |
format |
Text |
author |
Bowline, M. D. Sojka, Jan Josef Schunk, Robert W. |
author_facet |
Bowline, M. D. Sojka, Jan Josef Schunk, Robert W. |
author_sort |
Bowline, M. D. |
title |
Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
title_short |
Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
title_full |
Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
title_fullStr |
Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
title_full_unstemmed |
Relationship of Theoretical Patch Climatology to Polar Cap Patch Observations |
title_sort |
relationship of theoretical patch climatology to polar cap patch observations |
publisher |
Hosted by Utah State University Libraries |
publishDate |
1996 |
url |
https://digitalcommons.usu.edu/physics_facpub/178 https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1177&context=physics_facpub |
long_lat |
ENVELOPE(-85.940,-85.940,79.990,79.990) |
geographic |
Canada Eureka Greenland Svalbard |
geographic_facet |
Canada Eureka Greenland Svalbard |
genre |
Greenland Svalbard |
genre_facet |
Greenland Svalbard |
op_source |
All Physics Faculty Publications |
op_relation |
https://digitalcommons.usu.edu/physics_facpub/178 https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1177&context=physics_facpub |
op_rights |
Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact the Institutional Repository Librarian at digitalcommons@usu.edu. |
op_rightsnorm |
PDM |
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1766020156221292544 |