ISWAT - International Space Weather Action Teams 

Within this magnetic comet tail other currents are driven by the motion of plasmas in the defining magnetic field, like

• the cross-tail current maintaining the elongated magnetic tail,
• magnetic field-aligned currents, coupling this tail currents and some of the magnetopause surface currents to the highly conduction upper atmosphere, and
• the ring currents, which are determined by plasma drift motion in the gradients and curvature of the closed dipole field.
• At the bottom end of the magnetospheric field-aligned current electric charges, and also electric fields created by the mapping of a general convection of magnetospheric fields imposed by the solar wind, set up a complicated system of ionospheric currents, which depends on both the initial driving fields, but also on the particular ionospheric conductivities created by the precipitation of energetic particles from the magnetosphere. Such ionospheric currents are referred to as auroral electrojets, and they couple back to the magnetospheric current sources via diverging currents at any ionospheric conductivity gradients. Depending on the importance and dominance of certain solar wind drivers this complicated coupled system of current sinks and sources can take a variety of complicated shapes, and even dynamic and short-lived structures. It can furthermore cover a wide range of longitudes and both high to medium latitudes, depending again on the strength and energy of the original solar wind drivers.

Another independent and strictly ionospheric current system at lower latitudes is coupled to plasma flow and related electric field structures around the almost horisontal portions of the magnetic dipole field close to the magnetic equator, the so called equatorial electrojets. These are rather depending on the variable solar radiation than the variable solar wind itself, which is the most important driver for the high-latitude ionospheric and all magnetospheric currents systems.

At any moment in time (also depending on the pre-history of each event) the entity of coupled magnetic and ionospheric current systems determines the geomagnetic environment for our man-made infrastructure. Any rapid changes in the current flow within this environment will generate strong electric fields, which in turn can generate strong induced currents in the ground and thus affect any extended conducting structures within our man-made infrastructure. Depending on the strength and variability of the solar wind, which drives the original magnetospheric current systems, the resulting coupled current systems in the upper atmosphere can be so large, change so rapidly and extend so far equatorward that major and crucial parts of our electrical (powerlines) and transport (pipelines and rails) infrastructure can be affected by such induced currents in the ground or within the infrastructure itself. The character of the current changes, and their temporal and spatial behaviour and extent, determines how dangerous - or rather how damaging – the induced current can impact on our infrastructure and its crucial nodal points such as joints, ends or, indeed, transformators.

Driving:

• the relative role of direct solar wind drivers such as magnetic field direction and strength, plasma density, temperature and velocity on the generation of currents and energisation of plasma in the various coupled magnetospheric regions;
• the roles of any combined varieties, or even temporal sequences of any such drivers on the resulting magnetospheric current systems and their variability;
• the role of the temporal (and maybe even spatial) extent of any such drivers, or their combinations, or their sequences affecting the magnetosphere;
• how the resulting magnetospheric current systems are different for low, moderate or extreme solar wind drivers, and how much they may depend on the prehistory of the solar wind driving.

Coupling:

• the exact physical mechanisms which determine the partition of stored magnetic energy in the magnetosphere in the regimes of magnetopause currents, tail currents, ring currents and the coupled ionospheric currents;
• the exact physical mechanisms which determine how these current systems couple to the upper atmosphere and thereby extract both energy and plasma from the magnetosphere, but also extract heavier plasma from the atmosphere, which in turn affects the overall energy content and thus stability of the original magnetospheric currents;
• the exact physical mechanisms how additional solar wind or internal drivers (or their variability) can affect, trigger or at least determine the excitation of either waves or instabilities in this coupled geospace system of currents and plasma, such that the system itself or only parts of it can rapidly increase or decay, e.g. substorms, or magnetic spikes in storms.
• the exact physical mechanisms which determine both location and time, and also amplitude, extent and duration of any such rapid or slow changes in any of the coupled current systems;

Impact:

• the combined impact of rapid magnetic changes for any type of extent, duration and amplitude - and thus even their repetitiveness - on any particular part of our man-made infrastructure, which would potentially be exposed to it;
• the vulnerability of any such infrastructure to a determined variety of imposed rapid changes in induced electric fields from variable ionospheric or magnetospheric currents;
• the additional role of soil, ocean or crustal conductivities on the enhancement or modification of any such electric fields induced by the geomagnetic disturbances
• the combinations of risk factors originating from localised magnetic disturbances (occurring almost anywhere at random), with structures in the surface and crustal conductivities and/or any exposed structures in the potentially affected infrastructure itself.

The ultimate proof for that we understand - and in the end have determined - the most important physical processes in this coupled system will be our ability to model the temporal and spatial behavior of the geomagnetic environment of a variety of solar wind drivers, also dependent on their sequence, combination and time history. Thus the scientific work of physical event-studies and statistical investigations must go hand in hand with an ever improving coupled model effort.

• Advance modeling capability of coupled geospace system.
• Understand and quantify spatial and temporal features of geomagnetic variability in response to external and internal drivers.
• Understand and quantify sub-storms initiation and dynamics.
• Understand and quantify relative role of different magnetized solar wind plasma and field parameters on the generation of electric currents and energization of plasma in various regions of coupled geospace system.
• Understand the role of  pre-history of driving.
• Understand and quantify differences in magnetospheric current systems  for low, moderate or extreme solar wind drivers.
• Understand and quantify effects of coupling between  ionosphere-magnetosphere current systems and processes in upper atmosphere.
• Understand and quantify properties of the high latitude region, including particle precipitation, conductivities, electric fields, neutral winds, currents, electromagnetic energy input, and Joule heating.
• Review of geomagnetic activity indices and activity scales.
• Assessment of capabilities to forecast geomagnetic environment variability.
• Assessment of capabilities to forecast magnetopause position.
• Assessment and improvement of capabilities to model auroral boundaries.
• Understand and quantify role of soil, ocean or crustal conductivities on the enhancement or modification of any electric fields induced by the geomagnetic disturbances.
• Understand and quantify impact of geomagnetic variability on critical infrastructure. 
• Quantification of extreme GIC characteristics.
• Generating inputs to global space weather roadmap.