Solar wind driving of magnetospheric ULF waves: Pulsations driven by velocity shear at the magnetopause
By Seth G. Claudepierre, S. Elkington, Michael Wiltberger. 2008
223 citations recorded by the source corpus.
[1] We present results from global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind/magnetosphere interaction. These MHD simulations are used to study ultra low frequency (ULF) pulsations in the Earth's magnetosphere driven by shear instabilities at the flanks of the magnetopause. We drive the simulations with idealized, constant solar wind input parameters, ensuring that any discrete ULF pulsations generated in the simulation magnetosphere are not due to fluctuations in the solar wind. The simulations presented in this study are driven by purely southward interplanetary magnetic field (IMF) conditions, changing only the solar wind driving velocity while holding all of the other solar wind input parameters constant. We find surface waves near the dawn and dusk flank magnetopause and show that these waves are generated by the Kelvin-Helmholtz (KH) instability. We also find that two KH modes are generated near the magnetopause boundary. One mode, the magnetopause KH mode, propagates tailward along the magnetopause boundary. The other mode, the inner KH mode, propagates tailward along the inner edge of the boundary layer (IEBL). We find large vortical structures associated with the inner KH mode that are centered on the IEBL. The phase velocities, wavelengths, and frequencies of the two KH modes are computed. The KH waves are found to be fairly monochromatic with well-defined wavelengths. In addition, the inner and magnetopause KH modes are coupled and lead to a coupled oscillation of the low-latitude boundary layer. The boundary layer thickness, d, is computed and we find maximum wave growth for kd = 0.5–1.0, where k is the wave number, consistent with the linear theory of the KH instability. We comment briefly on the effectiveness of these KH waves in the energization and transport of radiation belt electrons.
Subfields: Astronomy and Astrophysics, Molecular Biology
View Paper: https://www.semanticscholar.org/paper/abf23714c5262ccbde73797bf5859b4e4765f8f7
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Citations in the corpus
- The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP (2013, background): “Ultra Low Frequency Waves (2–100 mHz) are excited at the magnetopause boundary in response to velocity shear (Claudepierre et al. 2008) or solar wind pressure fluctuations (Ukhorskiy et al. 2006; Claudepierre et al. 2009).”
- The interaction of ultra-low-frequency pc3-5 waves with charged particles in Earth’s magnetosphere (2017, background): “ULF waves excited by solar wind dynamic pressure variations have much larger amplitudes than VLF waves (Claudepierre et al. 2008; Zong et al. 2009a, b; Zhang et al. 2010) and hence the former can accelerate energetic particles at a much faster rate.”
- Source and seed populations for relativistic electrons: Their roles in radiation belt changes (2015, background): “Indeed, a distribution of mode numbers is possible up to m> 15, particularly during times of high-speed solar wind [Elkington et al., 2012; Claudepierre et al., 2008].”
- Radiation belt dynamics: The importance of wave‐particle interactions (2010, background): “[4] Ultra Low Frequency (mHz) waves are excited at the magnetopause boundary in response to velocity shear [Claudepierre et al., 2008] or solar wind pressure fluctuations [Ukhorskiy et al., 2006; Claudepierre et al., 2009].”
- Energetic electron response to ULF waves induced by interplanetary shocks in the outer radiation belt (2009, background): “[6] The ULF waves, on the other hand, can be excited with much larger amplitudes than the VLF waves in the magnetosphere by Kelvin-Helmholtz instability [Kivelson and Pu, 1984; Hudson et al., 2004; Claudepierre et al., 2008 ] and solar wind dynamic pressure variations [Kepko and Spence, 2003; Hudso”