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Fig. 3 | Earth, Planets and Space

Fig. 3

From: Two current systems in the preliminary phase of sudden commencements in the magnetosphere

Fig. 3

Snapshots of the electric current systems at t = 5.5 min as seen from the post-noon point in the northern hemisphere. The color of the electric current lines denotes \({J}_{\parallel }/|{\varvec{J}}|\) (blue: antiparallel, white: perpendicular, red: parallel to the magnetic field). The red and blue shadings in the lower boundary (the sphere of \(r=3{\mathrm{R}}_{\mathrm{e}}\)) indicate downward and upward FACs, respectively. AH and AL indicate the projection of both areas in the ionosphere (Fig. 2) to the lower boundary. The white arrows represent the directions of the currents. The white dotted lines indicate the demarcation between the inner magnetosphere and the outer magnetosphere. The pressure in the equatorial plane and that in the noon–midnight meridian are shown with color contour lines. The type H current system from AH consists of two FACs on the pre-noon sector and the post-noon sector and the FPC connecting these two FACs. The type L current system from AL is made up of the downward FAC and the electric current in the magnetosheath via the FPC across the magnetopause. Some current lines from AL belong to the type L current system

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