Joint Cluster/Ground‐Based Studies in the First 20 Years of the Cluster Mission

Ground‐based facilities make an important contribution to our understanding of the magnetospheric system. Coordination with ground‐based facilities has been embedded within the Cluster mission since before launch, and this has given rise to a large number of studies which have exploited data from both Cluster and one or more of the diverse range of ground‐based instrumentation that have been available during the mission timespan. In this paper, we review the advances that have been made to our understanding of the magnetosphere‐ionosphere system, in which insight has been enhanced by combining ground‐based observations with observations from Cluster. Topics covered span from the bow shock to the magnetotail and down to the aurora. Key Points Space‐ and ground‐based measurements strongly complement each other, and combining the two further enhances the insight they provide Studies exploiting ground‐based observations have been a key aspect of the Cluster mission, yielding approximately 100 papers We review these studies, covering the full range of solar wind/magnetosphere/ionosphere coupling and dynamics