Time evolution of various significant variables in the calculation for the third harmonic illustrated in Fig. 7. Left panel: maximum of the field. Middle panel: location of the singular points, where the upper curve is for L(t), and the lower one for L_cs(t). Right panel: value of the flux integral in the central lobe of the solution. In each panel, the result of the Bifrost calculation is shown as a black solid line; the power laws derived from Eqs. (13)–(15) are shown as red dashed lines.