The role of Kelvin-Helmholtz waves in the dynamics of the dayside magnetopause and the inner magnetosphere

Abstract:

Observational studies using data from multipoint spacecraft combined with ground-based measurements are presented to understand the role of the low-frequency waves commonly observed along the Earth’s magnetopause and in the low-latitude boundary layer (LLBL). Typical physical processes occurring at the magnetopause boundary layer include Kelvin-Helmholtz waves generated by shear flows, which provide multiple paths to affect inner-magnetospheric particle density and energy fluxes. In particular, nonlinearly-developed forms of Kelvin-Helmholtz waves, called Kelvin-Helmholtz vortices, generate field-aligned currents via vortical motion of plasmas that leads to a twist or magnetic shear of the flux tube. A clockwise (counter-clockwise) rotation, as viewed in the direction of the magnetic field, in association with Kelvin-Helmholtz vortices in the dusk (dawn) flank of the magnetopause leads to upward (downward) field-aligned current inside the flux tube. We present in-situ Cluster, THEMIS, and FAST spacecraft observations of Kelvin-Helmholtz vortices and associated physical processes that map to the poleward edge of the auroral regions together with ground-based observations (magnetograms, riometer data, and all sky images) to link boundary fluctuations to variations of the inner magnetospheric/ionospheric phenomena.