Author : Ryan Hobson Smith
Publisher :
ISBN 13 :
Total Pages : 196 pages
Book Rating : 4.:/5 (81 download)
Book Synopsis Effects of Ionospheric Conductance on Magnetosphere-ionosphere Coupling by : Ryan Hobson Smith
Download or read book Effects of Ionospheric Conductance on Magnetosphere-ionosphere Coupling written by Ryan Hobson Smith and published by . This book was released on 2012 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: As mankind becomes more reliant on space systems and vulnerable to the effects of space weather, creating a comprehensive understanding of the near earth space environment has become increasingly important. Observational data about this environment comes from orbiting satellites or from ground-based measurements. In the statistical analysis of these observations, there is an oft observed and currently unexplained dawn-dusk asymmetry in the flow of plasma through the nightside plasma sheet region of the magnetosphere, as well as in the Alfvénic aurora in the ionosphere. This thesis uses a version of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) code to examine generation of asymmetry in the magnetosphere-ionosphere system. Controlled simulations using the LFM global model demonstrate that the dawn-dusk asymmetry in plasma sheet flow bursts and Alfvénic auroral power are regulated by the spatial variation in ionospheric conductance. This asymmetry disappears when the conductance is taken to be spatially uniform. Careful examination of currents in the ionosphere shows that the spatial variation in conductance skews the anti-sunward convection of plasma. Analysis indicates that typical distributions of conductance in the ionosphere will induce a clockwise rotation of the convection pattern over the polar cap region. This clockwise rotation causes the closure of open magnetic fiux in the magnetotail to occur preferentially on the duskside, resulting in the observed duskside enhancements in the plasma flow and Alfvénic aurora. Futhermore, non-physical spatial variations in the ionospheric conductance can be used to produce counterclockwise rotations in the convection pattern, leading to increased rates of reconnection and enhancements of plasma flow and Alfvénic aurora on the dawn side of the plasma sheet.