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A new approach has been developed to reconstruct the magnetospheric configurations from data by directly representing the magnetic field as a sum of divergence-free contributions from a set of diffuse bubble-like field sources, more or less evenly distributed over the modeling region. Unlike the earlier suggested method based on the radial basis functions, the new fully local approach does not involve toroidal and poloidal fields, which makes it conceptually simpler and computationally more straightforward. The method has been tested on artificial data sets generated using an empirical model and aglobal magnetohydrodynamic simulation. The new model was shown to faithfully reconstruct the high-latitude magnetospheric structures, such as the field-aligned currents and the diamagnetic depression in the outer polar cusp funnels. The new method can serve as a flexible tool with a tunable resolution and varied focus area, to be used in the data-based modeling of the magnetosphere.

Plain Language Summary A novel approach is proposed, superior to the previously used ones, to quantitatively describe 3-D configurations of the geospace magnetic field. The new method makes it possible to mathematically represent spatial distributions of the magnetic field with a desired resolution in space and allows one to focus the modeling on different areas of the Earth's magnetosphere, in a way similar to using a magnifying glass when studying material objects of different sizes. The proposed approach has been tested on data, obtained in a numerical simulation of the Earth's magnetosphere, and demonstrated its ability to faithfully model the polar cusp funnels, where the solar wind penetrates into the magnetosphere, as well as the magnetic effects of the field-aligned currents, connecting the interplanetary medium with the terrestrial ionosphere.