Use of a hybrid code for global-scale simulation of the Earth's magnetosphere

Abstract

An understanding of the Earth's magnetosphere and the magnetospheric substorm requires an ability to simulate kinetic processes in a global context. To this end we have developed a hybrid code with a number of innovative features: (1) The code uses a general curvilinear coordinate grid enabling it to accommodate disparate size scales. (2) The cold, dense plasma inside the plasmapause, where kinetic effects are unimportant, is treated in the fluid approximation. There is a seamless interface between the fluid and kinetic descriptions. (3) The field update is subcycled to the particle update to circumvent the Courant condition with respect to the propagation of Alfvén and whistler mode waves. A two-dimensional version of the code has established a causal link between events in the plasma sheet and the filamentary currents carried by auroral electrons. We are now embarking on the development of a full three-dimensional code for the coupled ionosphere–magnetosphere–magnetosheath system. The simulation domain is comprised of seven discontinuously joined coordinate patches. The Earth's ionospheric shell constitutes one of the boundary surfaces.