Ground-based imaging of magnetospheric boundaries

The ionosphere provides an excellent window on magnetospheric and solar wind processes. Often discrete magnetospheric boundaries are imaged in the ionosphere. These boundaries can be detected by a variety of experimental techniques, but each has strengths and weaknesses; these are summarised here. Often ionospheric proxies are used for magnetospheric boundaries. Whilst their use has led to important new insight into geospace processes, some limitations are also apparent. Illustrations using the open/closed field line boundary both on the dayside and the nightside are given. The future direction of ground-based imaging of magnetospheric boundaries is discussed. The key issues are reliable identification of further magnetospheric boundaries such as near-Earth neutral x-line, improvements to the ground-based experiment network to improve the spatial and temporal resolution, and the coverage, development of data assimilation and visualisation techniques, as well as the definition of additional value-added data products.