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Modeling of the coupled magnetospheric and neutral wind dynamosWork at SRI involved modeling the exchange of electromagnetic energy between the ionosphere and magnetosphere to help interpret the DE-B Poynting flux observations. To describe the electrical properties of the high-latitude ionosphere, we constructed a numerical model, from the framework provided by the Vector Spherical Harmonic (VSH) model, that determines the ionospheric currents, conductivities, and electric fields including both magnetospheric inputs and neutral wind dynamo effects. This model development grew from the earlier question of whether an electrical energy source in the ionosphere was capable of providing an upward Poynting flux. The model solves the steady-state neutral wind dynamo equations and the Poynting flux equation to provide insight into the electrodynamic role of the neutral winds. The modeling effort to determine the high-latitude energy flux has been able to reproduce many of the large-scale features observed in the Poynting flux measurements made by DE-2. Because the Poynting flux measurement is an integrated result of energy flux into or out of the ionosphere, we investigated the ionospheric properties that may contribute to the observed flux of energy measured by the spacecraft. During steady state the electromagnetic energy flux, or DC Poynting flux, is equal to the Joule heating rate and the mechanical energy transfer rate in the high-latitude ionosphere. Although the Joule heating rate acts as an energy sink, transforming electromagnetic energy into thermal or internal energy of the gas, the mechanical energy transfer rate may be either a sink or source of electromagnetic energy. In the steady state, it is only the mechanical energy transfer rate that can generate electromagnetic energy and result in a DC Poynating flux that is directed out of the ionosphere.
Document ID
19950016673
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Thayer, J. P. (SRI International Corp. Menlo Park, CA, United States)
Vickrey, J. F. (SRI International Corp. Menlo Park, CA, United States)
Heelis, R. A. (Texas Univ. at Dallas, Richardson, TX., United States)
Gary, J. B. (Texas Univ. at Dallas, Richardson, TX., United States)
Date Acquired
September 6, 2013
Publication Date
March 8, 1995
Subject Category
Geophysics
Report/Patent Number
NAS 1.26:197861
SRI PROJ. ESU-4604
NASA-CR-197861
Accession Number
95N23090
Funding Number(s)
CONTRACT_GRANT: NAGW-3508
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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