Intervals of Steady Magnetospheric Convection (SMC) are loosely defined as times when convection in the magnetosphere as a whole is enhanced and there are no substorm signatures. A lack of substorm signatures implies that the large scale structure of the magnetotail is maintained. There have been several quantitative methods developed to detect SMC events. None of these methods are based on observations of convection. The Super Dual Auroral Radar Network (SuperDARN) is a useful tool for studying SMC, because it gives a direct measurement of convection on a global scale. Previous SMC selection methods have made use of ground based magnetometer responses to auroral currents in the atmosphere. These methods resulted in a strong seasonal dependence in SMC occurrence due to seasonal changes in ionospheric conductivity. A new SMC selection criterion was developed to improve upon the previous criteria. This new method identifies all the events found using currently accepted methods plus additional intervals that reduce the seasonal dependence in SMC occurrence. SuperDARN was used to evaluate the old and new selection methods. According to SuperDARN convection observations, the new SMC selection criterion largely eliminated ionospheric conductivity effects. A conceptual model of the conductivity effects on the traditional SMC selection method was developed, and the occurrence of modelled SMC events agrees well with observations. Statistical studies have revealed that the additional SMC intervals have similar properties as events selected using traditional methods. Case studies confirmed the statistical results that SMCs selected by the new criterion have SMC properties. Both SMC events sets have a moderate solar wind driver, enhanced convection, and stable polar cap size. Statistical studies have also shown there was good SuperDARN data coverage during SMC, which is not typical of SuperDARN observations during enhanced and disturbed conditions in the magnetosphere. It is therefore shown to be an excellent tool with which to study SMC.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-06302008-131440 |
| Date | 08 July 2008 |
| Creators | Pfeifer, Jeff Bruce |
| Contributors | Manson, A, Moewes, A., Hussey, G., Koustov, A.V., McWilliams, K., Merriam, J. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-06302008-131440/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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