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Kinetic Alfven Waves From Magnetotail to the Ionosphere in Global Hybrid Simulation Associated With Fast Flows


Cheng, Lei
Lin, Yu
Perez, J
Johnson, Jay
Wang, Xueyi


We have used the Auburn Global Hybrid Code in 3-D to study the generation, dynamics, and global structure of kinetic Alfven waves (KAWs) from the magnetotail to the ionosphere. Our results show that KAWs are generated in magnetic reconnection in the plasma sheet, located around fast flows, and carrying transverse electromagnetic perturbations, parallel Poynting fluxes, parallel currents, and parallel electric field. Overall, shear Alfvenic turbulent spectrum is found in the plasma sheet. The KAWs are shear Alfven waves possessing short perpendicular wavelength with k(perpendicular to)rho(i) similar to 1, where k(perpendicular to) is the perpendicular wave number and rho(i) the ion Larmor radius. The KAWs are identified by their dispersion relation and polarizations. The structures of these KAWs embedded in the plasma sheet are also revealed by placing a virtual satellite in the tail. In order to understand whether the Poynting fluxes carried by the shear Alfven waves/KAWs in the plasma sheet can be carried directly along field lines to the ionosphere, we have tracked the wave propagation from the plasma sheet to the ionosphere. It is found that in front of the flow-braking region, the structure and strength of the shear Alfven waves are significantly altered due to interaction with the dipole-like field, mainly by the flow shear associated with the azimuthal convection. Also in front of the dipole-like field region, ion kinetic effects (Hall effects) lead to the generation of additional pairs of KAWs. As such, the generation and transport of the shear Alfven waves/KAWs to the ionosphere are illustrated for the first time in a comprehensive manner on the global scale.