State of the art and future multi-spacecraft observations of the auroral acceleration region.
Colin Forsyth
A. N. Fazakerley (UCL MSSL), I. J. Rae (UCL MSSL), C. J. Owen (UCL MSSL)
The auroral acceleration region couples cold plasma in the ionosphere with hot plasma in the magnetosphere. In this region, charged particles are accelerated to high energies along the magnetic field, converting electromagnetic energy into particle kinetic energy necessary for generating the aurora in the ionosphere. Observations from single spacecraft missions, such as FAST, Freja and Viking, provided the basis of much of our knowledge about this region. However, this single spacecraft approach cannot determine the temporal variability or the altitudinal structure of this region; observations which are key to unravelling the physics controlling the acceleration of particles. Over its lifetime, the four-spacecraft Cluster mission has provided new insights into the auroral acceleration process. Here, we will show how observations from Cluster have shown that variations in quasi-static particle acceleration occurs on timescales of a few minutes and is concentrated at low altitudes, providing new insights into the acceleration mechanisms. We will also show how in future, dedicated multi-spacecraft missions with payload that is optimized for observing both the in-situ plasma conditions and remote sensing the aurora are necessary in order for us to uncover more of the fundamental plasma physics of this key region of the magnetosphere.