Show simple item record

Modelling of plasmaspheric flows.

dc.contributor.authorGuiter, Steven Marken_US
dc.contributor.advisorGombosi, Tamas I.en_US
dc.date.accessioned2014-02-24T16:13:34Z
dc.date.available2014-02-24T16:13:34Z
dc.date.issued1992en_US
dc.identifier.other(UMI)AAI9308325en_US
dc.identifier.urihttp://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:9308325en_US
dc.identifier.urihttps://hdl.handle.net/2027.42/103224
dc.description.abstractFlows on a plasmaspheric flux tube were modelled, using a fully interhemispheric model in which no low speed assumptions are made. The model is time-dependent and hydrodynamic; it is an adaptation, for closed dipolar field lines, of a polar wind model developed by Gombosi et al. (1985). Both one- and two-stream versions were developed. The model simultaneously solves the coupled continuity, momentum, and energy equations of a two-ion (H$\sp+$ and O$\sp+$) quasineutral, currentless plasma. The coupled time-dependent partial differential equations are solved using a combined Godunov scheme/Crank-Nicolson method with dimensional splitting. The model takes into account the effects of ionization, charge exchange, recombination, collisions, heat conduction, and allows for external heat sources. The model flux tube connects external reservoirs, each at an altitude of 200 km; these reservoirs represent photochemically controlled regions of the ionosphere. The neutral species densities and the neutral temperature are found using the MSIS-86 model (Hedin, 1987). The one-stream version of this model has been used to investigate plasmaspheric refilling following density depletions on an L = 2 flux tube, which were simulated by dividing steady state ion densities by an arbitrary factor above 2500 km altitude; to study the effect of equatorially confined H$\sp+$ heating on an L = 4 flux tube; to model diurnal variations on an L = 2 flux tube; and to investigate annual variations in plasmaspheric density. The two-stream version was used to study plasmaspheric refilling on an L = 4 flux tube following a density depletion; the initial H$\sp+$ density profiles were chosen to be similar to those used by Rasmussen and Schunk (1988). The results from the plasmaspheric refilling studies indicate that for an initial period refilling occurs from the equator downward, between downward moving shocks. The study of equatorially confined H$\sp+$ heating showed that heating rates which are consistent with observed magnitudes of warm, trapped, anisotropic plasma would not significantly affect the thermal population. The most striking result from the diurnal variations study was the large downward H$\sp+$ velocity which occurs in the southern end in the early morning. The study of annual variations in plasmaspheric density showed that these are due to variations in O$\sp+$ density in the upper ionosphere. The results found with the model are generally consistent with those found in earlier work; significant differences include temperature variations, as were seen in the refilling studies, and strong transients, as were found in the diurnal variations study.en_US
dc.format.extent165 p.en_US
dc.subjectPhysics, Atmospheric Scienceen_US
dc.subjectPhysics, Fluid and Plasmaen_US
dc.titleModelling of plasmaspheric flows.en_US
dc.typeThesisen_US
dc.description.thesisdegreenamePhDen_US
dc.description.thesisdegreedisciplineAtmospheric and Space Sciencesen_US
dc.description.thesisdegreegrantorUniversity of Michigan, Horace H. Rackham School of Graduate Studiesen_US
dc.description.bitstreamurlhttp://deepblue.lib.umich.edu/bitstream/2027.42/103224/1/9308325.pdf
dc.description.filedescriptionDescription of 9308325.pdf : Restricted to UM users only.en_US
dc.owningcollnameDissertations and Theses (Ph.D. and Master's)


Files in this item

Show simple item record

Remediation of Harmful Language

The University of Michigan Library aims to describe library materials in a way that respects the people and communities who create, use, and are represented in our collections. Report harmful or offensive language in catalog records, finding aids, or elsewhere in our collections anonymously through our metadata feedback form. More information at Remediation of Harmful Language.

Accessibility

If you are unable to use this file in its current format, please select the Contact Us link and we can modify it to make it more accessible to you.