Kinetic Alfvén Waves From Magnetotail to the Ionosphere in Global Hybrid Simulation Associated With Fast Flows. Issue 2 (3rd February 2020)

• Record Type: Journal Article
• Authors: Cheng, Lei; Lin, Yu; Perez, J. D.; Johnson, Jay R.; Wang, Xueyi
• Is Part Of: Journal of geophysical research. Volume 125:Issue 2(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-03
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2019JA027062
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We have used the Auburn Global Hybrid Code in 3‐D to study the generation, dynamics, and global structure of kinetic Alfvén 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 Alfvénic turbulent spectrum is found in the plasma sheet. The KAWs are shear Alfvén waves possessing short perpendicular wavelength with k ⊥ ρ i ∼ 1, where k ⊥ is the perpendicular wave number and ρ 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 Alfvén 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 Alfvén 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 Alfvén waves/KAWs to the ionosphere are illustrated for the first time in a comprehensive manner on the global scale. Key Points: Global evolution of kinetic Alfvén waves (KAWs) from the magnetotail to the ionosphere is analyzed using a 3‐D global hybrid simulation KAWs are shown to be generated in the plasma sheet by reconnection and in the flow‐braking region due to ion inertial effect Dipole‐like field region alters the structure and strength of the shear Alfvén waves that propagate to the ionosphere