Characteristics of the Particle Acceleration and Density Cavities Associated With Large-Scale Aurora During Auroral Substorms

Abstract:

The auroral acceleration region is a key region of interest in auroral and magnetospheric physics. It became accessible for in situ multi-probing for the first time in early 2009, by the Cluster swarm. The unique multi-point data collected in the AAR has been used to address and resolve various open issues on the acceleration processes, such as: (1) the altitude distribution of the parallel electric field and associated potential structures and their stability and evolution; (2) the relative role of and interaction between quasi-static and Alfvénic acceleration for producing large-scale auroral forms and surges; (3) acceleration and electrodynamics features, such as current closure of large-scale auroral forms and surges; (4) the altitude distribution of the plasma density on auroral field lines with respect to geocentric altitude, the auroral density cavity, and the auroral acceleration region. Crucial for the interpretations of the in situ multi-point data in many of the event studies presented here, was the use of DMSP satellite imager data, providing an overview of the auroral distribution close in time and space to the Cluster oval crossings.