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withers

HR: 0800h
AN: SA51A-0237
TI: New Theoretical Tools for Studying Ionospheric Electrodynamics
AU: * Withers, P
EM: withers@bu.edu
AF: Boston University, Center for Space Physics, 725 Commonwealth Avenue, Boston, MA 02215, United States
AB: Two different theoretical approaches are commonly used to study ionospheric plasma motion. Dynamo theory and the conductivity equation is used to study currents caused by plasma motion. Ambipolar diffusion models are used to study changes in plasma density caused by vertical plasma motion. The conductivity equation, which states that the current density vector equals the product of the conductivity tensor and the electric field vector, is derived from the conservation of momentum equations after the effects of gravity and pressure gradients are neglected. These terms are crucial for ambipolar diffusion. The two different theoretical approaches are inconsistent. On Earth, the dynamo region (75 km to 130 km, altitude controlled by magnetic field strength and collision frequencies) occurs below regions (F region) where ambipolar diffusion affects plasma number densities, so the theoretical inconsistencies are rarely noticed. However, the inconsistencies are present in most thermosphere-ionosphere-electrodynamics models and will affect the results of such models, particularly in the F region. We present an extension of the conductivity equation that can self-consistently describe ionospheric currents and plasma diffusion.
DE: 2400 IONOSPHERE (6929)
DE: 2411 Electric fields (2712)
DE: 2437 Ionospheric dynamics
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting