The project SWESMAG relies on magnetic field data from Swarm to investigate Space Weather (SWE) effects related to Geomagnetic Induced Currents (GICs), driven mainly by rapid variations of the ionospheric Polar Electrojet (PEJ) currents and quantified (loosely) by the variation of the horizontal ground magnetic field component dH/dt.

Swarm spacecraft can observe in-situ the Field-Aligned Currents (FACs, closed by the curl-free component of the ionospheric current) and remotely the PEJ currents (essentially the complementary, divergence-free component), and by that both fundamental ionospheric current systems can be monitored at the same time.

 The Low Earth Orbit (LEO) of Swarm is also optimum for frequent passes over the whole globe and numerous conjunctions with ground magnetic stations, where dH/dt can be derived.

SWESMAG builds on the measurement chain provided by Swarm FAC and PEJ observations, together with dH/dt data from ground stations. In order to match FAC observations to SWE needs, a new Sheet FAC (SFAC) index is implemented, which quantifies the magnitude of the large-scale FAC system by the maximum absolute value of the magnetic perturbation for each Swarm crossing of the auroral oval.  

This synthetic characterization of the FAC is both appropriate for the near-real time regime (4 values per orbit, cadence of about 20-25 min per satellite) and suitable for comparison with PEJ intensity and dH/dt. 

Once the processing chain of SFAC and the correlation analysis of SFAC–PEJ–dH/dt are fully defined, a broader set of events will be selected and investigated. The work benefits from FAC tools developed under the SIFACIT project and implemented under Swarm VRE.  

While the results will be based on Swarm data, one can expect rather straight generalization to other LEO platforms. 

Project duration: November 2022 – October 2023. This project is funded by ESA via the Swarm DISC, Sub-Contract No. SW-CO-DTU-GS-130.