Kelvin-Helmholtz vortices and double mid-latitude reconnection at the Earth's magnetopause: Comparison between observations and simulations

Observational signatures of Kelvin-Helmholtz (K-H) vortices and of double mid-latitude reconnection are highlighted in satellite data of the THEMIS mission. It is shown that the plasma fluid quantities at the low-latitude flank of the Earth's magnetosphere are compatible with K-H vortices, as described by three-dimensional simulations. At the same time it is shown that the particle fluxes are compatible with the presence of magnetic-field lines, embedded in the K-H vortices, that close on Earth but are connected to the solar wind at low latitude. These field lines are generated during the K-H evolution by magnetic reconnection proceeding spontaneously in both hemispheres at mid-latitudes, allowing the solar-wind plasma to enter the Earth's magnetosphere directly.