Cross-Scale Magnetotail Convection: from Individual Properties and Impacts to Systems Understanding

Coupling of the solar wind and Earth’s magnetosphere is strongest during intervals of the southward interplanetary magnetic field (IMF), when magnetic reconnection at the subsolar magnetopause, with subsequent reconnection in the distant magnetotail, sets off a global convection cycle that transfers magnetic flux from the dayside into the magnetotail and then back to the dayside magnetosphere. Plasma sheet convection from the distant reconnection line to the inner magnetosphere exhibits a wide range of coupled multi-scale processes. Non-monotonic features in the plasma sheet magnetic terrain, such as minima, tailward gradients, or bumps in the northward component of the magnetic field lead to instabilities and  energy from transfer from large scale (~100 Earth radii) to mesoscale (~Earth radii) structures and earthward plasma flows. These in turn generate a wide range of kinetic scale (~100 km) phenomena which energize particles beyond 100 keV and produce bursts of particle precipitation into the atmosphere. In this paper we explore the properties and the role of mesoscale convection in the transport and acceleration of energetic electrons and ions from the magnetotail to the inner magnetosphere, from direct injections of particles into the radiation belt and the ring current, to generation of velocity instabilities that provide the pathway for the energy cascade from global to kinetic processes. We employ test-particle simulations in our Conservative Hamiltonian Integrator of Magnetospheric Particles (CHIMP) one way coupled to a high-resolution magnetohydrodynamic (MHD) simulations of plasma convection in the magnetotail. For the latter we use the Grid Agnostic MHD for Extended Research Applications (GAMERA) global magnetospheric model. We then use new modeling results and understanding of individual properties and impacts on plasmasheet dynamics to discuss Heliophysics Systems Observatory capabilities that would enable a system-wide view of cross-scale convection in Earth’s magnetotail.