Science opportunities for swarm-cluster coordination: Surveying the ring current and FACs

The imminent launch of the 3 Swarm spacecraft into low, polar Earth orbits; the planned coordination of Swarm with the 4 Cluster spacecraft through joint operations, and the further possible coordination with the recently launched 2 spacecraft RBSP mission, provides an unprecedented, distributed space dataset of `clustered' multi-point measurements. In anticipation of the direct comparison of Swarm and Cluster, preliminary study of the morphology and influence of the ring current using Cluster has produced a full-circle determination of the in-situ RC and associated FACs directly from the 4-spacecraft perigee observations. Such externally induced magnetic signals have significant effect at low Earth orbit (LEO) so that coordinated measurements of the current systems from ground to the (inner) magnetosphere are highly desirable and may be used to validate the Swarm constellation data. We present further investigations of the RC morphology and compare the significance of the connecting FACs and partial eastward current using analysis techniques derived from the calculation of curl(B) and magnetic gradients. We also investigate the consequences for future spacecraft constellations at both Cluster and Swarm, during potential joint operations.