"The European Cluster Assimilation Technology (ECLAT) programme will provide an unparalleled space plasma physics data repository and software tools archive for the Solar Terrestrial Physics community, building on the existing European Space Agency's Cluster Active Archive initiative. The Earth’s magnetosphere is the best observed space plasma environment in the universe, providing a wealth of information on fundamental plasma phenomena, planetary magnetospheric structure and behaviour, the environmental impact of the Sun-Earth connection, and the operational environment for space-based technology. However, the sheer volume of data available, the wide variety of observational methods and measurement types – in situ measurements, remote-sensing observations, modelling results, on micro-, meso-, and global scales – means that fully exploiting this incredible resource is extremely difficult. The objective of this proposal is to upgrade an already-existing European Space Physics Data Centre, the ESA Cluster Active Archive (CAA), increase its data holdings with a wide selection of additional data and to develop software tools to facilitate data-mining and data-visualization, to provide a research resource to the space plasma community that does not currently exist. One of the key aims of the proposal is to extend existing European magnetospheric modelling activities for inclusion in the CAA, with the ultimate aspiration being to develop “reanalysis” and assimilation technology to marry model output with observations to provide a holistic, synoptic 3D time-history of magnetospheric state, which will provide a contextual framework for interpretation of all other magnetospheric data-sets."