The project objectives are the following:

• Building the necessary software tools To develop an integrated software package, containing modules for data handling and visualization, intervals selection, data analysis, data simulation, consistency/validation tests etc. Modules developed for other scientific missions like Cluster or Champ, e.g. for spatial gradient estimation, magnetic field model subtraction, orbit simulation, statistical analysis etc, are adapted to the specificity of Swarm and integrated

• Estimating the accepted level of fluctuations To define the level of tolerable deviations from zero in div(B), curl(E) and div(V) due to 'natural' causes (measurement fluctuations, spatial-temporal inhomogeneity, orbital constraints etc.) by analyzing the performance of validation tests on synthetic data and on other (i.e. Cluster) multi-point satellite data. In the same way, the impact of using various additional constraits, to estimate the missing gradient components, is also assesed.

• Identification of data intervals suitable for the validation tasks This includes an automatic pre-selection of intervals with small satellite separation distance, quiet magnetospheric/ ionospheric periods, low data fluctuations etc, as well as a further refinement of the selection based on visual inspection, inter-satellite data comparison, identification of potential instrument artifacts, consistency checks etc.

• Performing the data validation and interpretation The results obtained by applying the validation tests on Swarm measurements is analyzed (comparison with simulation tests, consistency checks etc) and interpreted.