The properties of the plasma and magnetic fields in the magnetotail vary with changing solar wind conditions. There is evidence that when the IMF is southward, magnetic reconnection occurs in the magnetotail and the magnetospheric convection is enhanced. Substorms eject energetic particles in the plasma sheet into the inner magnetosphere. Some of these particles may precipitate into the high-latitude ionosphere, creating active auroras. Understandings of the dynamics of the magnetotail and its relation to the auroral ionosphere require multiple observations and theoretical simulations on different time scales. The observations include data obtained from satellites, such as ISTP, Cluster II, Double Star, ground-based facilities and future THEMIS probes. Interpretations of results derived from the data rely on executions of multi-scale MHD, hybrid, and particle codes. The main objective of this session is to study what physical processes control magnetotail structure, dynamics, and energy flow, and how the auroral ionosphere couples with the magnetotail. Results related to other Solar-Terrestrial Physics topics are also welcome.