Fig. 7

Evaluation indices in the period of 84 s using the data observed from 00:00 on October 26 to 00:00 on October 31 at site 142. The data in red correspond to the leverage data caused by the storm. a–d Show the variation in PD(\({{\varvec{E}}}_{x}\), \({{\varvec{H}}}_{x}\)), PD(\({{\varvec{E}}}_{x}\), \({{\varvec{H}}}_{y}\)), PD(\({{\varvec{E}}}_{y}\), \({{\varvec{H}}}_{x}\)), and PD(\({{\varvec{E}}}_{y}\), \({{\varvec{H}}}_{y}\)), respectively; e shows the variation in polarization direction for the magnetic field; and f shows the variation in the normalized hat matrix's diagonal element. There are preferred directions of the phase difference between the orthogonal electric and magnetic fields corresponding to the leverage data, as shown in b and c