Swarm observations of kilometer-scale low-altitude cusp/cleft ion upflow and downflow

Abstract:

The European Space Agency’s Swarm mission is used to study the physics of the F region cusp/cleft ion fountain. In brief, the cleft ion fountain is a region where large fluxes of terrestrial plasma, including relatively heavy ions such as oxygen, are observed to escape into space. Such atmospheric loss is driven by and can influence magnetospheric processes. The three Swarm satellites are well-suited for investigating the properties of the low-altitude ionospheric reservoir thought to be significant in supplying plasma for high-altitude outflows. Each satellite is instrumented to measure ion velocity, plasma density and temperature, and electric and magnetic fields at cadences of 2 samples/s and higher. We probe the structuring of ion upflow and downflow at kilometer scales by investigating the relationship between upflow and ion heating, electron heating, and field-aligned electric currents.