Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field
Thesis (M.S.) University of Alaska Fairbanks, 2005 Two meridian scanning photometers, one located in Alaska and one in Svalbard, are used to examine the behavior of the dayside aurora just before the onset of the expansion phase of 61 substorms. In a strong majority of cases (80%), a poleward moveme...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/6202 2023-05-15T18:29:50+02:00 Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field Andersen, Carl Stephen 2005-12 http://hdl.handle.net/11122/6202 en_US eng http://hdl.handle.net/11122/6202 Department of Physics Thesis ms 2005 ftunivalaska 2023-02-23T21:36:35Z Thesis (M.S.) University of Alaska Fairbanks, 2005 Two meridian scanning photometers, one located in Alaska and one in Svalbard, are used to examine the behavior of the dayside aurora just before the onset of the expansion phase of 61 substorms. In a strong majority of cases (80%), a poleward movement of the dayside aurora is seen in the minutes preceding sub storm onset. For the cases examined where a poleward movement of the dayside aurora is seen, a northward turning of the (generally southward) IMF is usually, but not always, seen. This suggests that for a majority of substorms, the 'trigger' is, or is related to, a northward turning of the IMF which can be seen by the motions of the dayside aurora. The observed movements of the dayside aurora and supposed onset triggers begin, on average, 12 minutes before substorm onset, which is the period before on-set during which nightside 'auroral fading' is known to happen. Two opposite but not necessarily exclusive behaviors of ionospheric convection have also been reported to occur during this period before onset, namely a decrease and/or an increase in polar cap convection velocities. Radar measurements of ionospheric convection are examined for these events but do not show an easily identifiable characteristic behavior. Thesis Svalbard Alaska University of Alaska: ScholarWorks@UA Fairbanks Svalbard |
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Open Polar |
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University of Alaska: ScholarWorks@UA |
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ftunivalaska |
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English |
description |
Thesis (M.S.) University of Alaska Fairbanks, 2005 Two meridian scanning photometers, one located in Alaska and one in Svalbard, are used to examine the behavior of the dayside aurora just before the onset of the expansion phase of 61 substorms. In a strong majority of cases (80%), a poleward movement of the dayside aurora is seen in the minutes preceding sub storm onset. For the cases examined where a poleward movement of the dayside aurora is seen, a northward turning of the (generally southward) IMF is usually, but not always, seen. This suggests that for a majority of substorms, the 'trigger' is, or is related to, a northward turning of the IMF which can be seen by the motions of the dayside aurora. The observed movements of the dayside aurora and supposed onset triggers begin, on average, 12 minutes before substorm onset, which is the period before on-set during which nightside 'auroral fading' is known to happen. Two opposite but not necessarily exclusive behaviors of ionospheric convection have also been reported to occur during this period before onset, namely a decrease and/or an increase in polar cap convection velocities. Radar measurements of ionospheric convection are examined for these events but do not show an easily identifiable characteristic behavior. |
format |
Thesis |
author |
Andersen, Carl Stephen |
spellingShingle |
Andersen, Carl Stephen Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
author_facet |
Andersen, Carl Stephen |
author_sort |
Andersen, Carl Stephen |
title |
Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
title_short |
Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
title_full |
Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
title_fullStr |
Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
title_full_unstemmed |
Characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
title_sort |
characteristic behavior of the dayside aurora in the minutes leading up to substorm onset: evidence for external triggering of substorms by the interplanetary magnetic field |
publishDate |
2005 |
url |
http://hdl.handle.net/11122/6202 |
geographic |
Fairbanks Svalbard |
geographic_facet |
Fairbanks Svalbard |
genre |
Svalbard Alaska |
genre_facet |
Svalbard Alaska |
op_relation |
http://hdl.handle.net/11122/6202 Department of Physics |
_version_ |
1766213233895538688 |