Title: Field-Aligned Currents: Their morphology, evolution, source regions and generators. Team coordinator: Dr. Yulia V. Bogdanova, RAL Space, Rutherford Appleton Laboratory, STFC, Harwell Oxford, Didcot, OX11 0QX, Oxfordshire, UK; E-mail:
[email protected] Deputy team coordinator: Prof. Hermann Lühr, Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14467 Potsdam, Germany, E-mail:
[email protected] Abstract: Birkeland currents play a fundamental role in conveying stress and electric field in the coupled solar wind- magnetosphere-ionosphere-thermosphere system, as well as providing the channel for energy and momentum transfer between these systems. Knowledge of the field-aligned current (FAC) structure and dynamics is a key to understanding how solar wind energy is transferred from the magnetosphere to the ionosphere and thermosphere. In the last decade these current systems were extensively investigated based on the observations from low-orbiting satellites, CHAMP, Ørsted, DMSP, Iridium constellation, as well as inferred from SuperDARN radars and ground-based magnetometer network observations. Although significant progress has been made in our understanding of the statistical distribution, source regions, and evolution of the current systems in response to condition changes, there are still many open questions in need of investigation. In addition, uncertainties in accuracy and temporal resolution of the current estimations remain to be studied. So far little attention has been paid to small and medium-scale FACs. Due to their large amplitudes they are believed to play an important role for the energy input to the upper atmosphere. In this project we plan to combine the observations from different missions, including and most notably from ESA’s recently launched multi-spacecraft mission Swarm, which provides the most accurate estimates of small and medium-scale FACs to date.