Physics & provenance
Open the GAMERA + REMIX numerical-current viewer; this page is its idealized current-system counterpart.
Magnetic field lines and FAC legs are numerically traced in T96 + a centered dipole (30,500 nT equatorial surface field). GSM coordinates; distances in Earth radii. This is not IGRF.
The optional X–Z diagnostic is quantitative: it evaluates the displayed model field at Y=0 and plots Jy = (∂Bx/∂z − ∂Bz/∂x)/μ0. It spans X=−27…13 RE and Z=−30…30 RE. The field is zeroed outside the displayed T96 magnetopause so its boundary sheet is included; everything inside 5 RE is excluded because the internal-field contribution is not a magnetospheric current system. Red is conventional current toward +Y (dusk); blue is toward −Y (dawn).
The colored circuits are illustrative. Region 1 is the red current-system branch in Ganushkina et al. Figure 7: its dusk/dawn FACs join through the high-latitude Chapman–Ferraro/tail transition. Region 1 does not self-close across the polar cap. At dawn and dusk, Pedersen current instead connects Region 1 to Region 2; Region 2 then joins the partial ring current. Together these segments form one continuous R1–R2 circuit. The high-latitude perpendicular branch is schematic because T96 field-line tracing does not uniquely solve generator-region current closure.
Quiet/active are illustrative presets, not event reconstructions. Magnetic traces stop at Earth or 25 RE; a domain-limit endpoint does not prove an open field line. No conductance, electric potential or charge evolution is solved. The substorm wedge follows Ganushkina et al. Figure 9b: blue dawn-to-dusk tail-current feeders connect to pink downward dawn/postmidnight FAC, a westward auroral electrojet, and upward dusk/premidnight FAC. The circuit returns on the magnetopause, rather than through an isolated reverse equatorial arc. Five neighboring T96 FAC traces at 65.2–66.4° form the ribbon width; their connecting tail feeders and boundary return are schematic. The wedge toggle includes the entire diverted circuit. This is a static topology illustration, not a simulated substorm or a current-amplitude estimate. BCBF channels are dashed white E×B plasma-flow paths, not electrical currents. General Hall electrojets and cusp/NBZ systems are omitted.
Ganushkina et al. current-systems review · Substorm wedge · BCBF versus SAID · T96 implementation · geopack
Numerical traces (HDF5) · Generation script