Comparison of the Lorentz force density f_z (a)–(c) and the alternative Lorentz force density ﹩{s}_{z}^{\mathrm{ad}}﹩ (d)–(f) at three different times during the eruption phase, viewed along a vertical cut at y = 0. The vertical component is presented in the color scale. Vectors indicate f_x, f_z (panels (a)–(c)) and ﹩{s}_{x}^{\mathrm{ad}}﹩, ﹩{s}_{z}^{\mathrm{ad}}﹩ (panels (d)–(f)). Vectors f_x, f_z are multiplied by a factor of 5. The black contour lines mark the current density at levels ﹩| {\boldsymbol{j}}| =1.1﹩, 3.0, and 6.0 (see Figure 11) and show an inverted Y-shape. All units are dimensionless. The animation begins at ﹩t=164{t}_{A}﹩ and ends at ﹩t=244{t}_{A}﹩.

(An animation of this figure is available.)

The video/animation of this figure is available in the online journal.