Magnetospheric response of two types in PSc geomagnetic pulsations to interaction with interplanetary shock waves

Using the June 22, 2015 event as an example, we present new data confirming the presence of a precursor of the sudden magnetic impulse caused by a powerful interplanetary shock wave (ISW). The precursor in the form of a train of oscillations (broadband pulse) with a falling frequency in the range 0.25 divided by 11 Hz with a duration of similar to 20 s, which had a spectral resonance structure, was recorded globally by a network of induction magnetometers at 18:33:27 UT. No significant phase delays of the signals were detected in four frequency bands at widely spaced observatories. It is suggested that the impulse can be excited in the Earth - ionosphere waveguide by a pulsed electric field which occurs in the ionosphere due to the short-term impact of ISW on the magnetosphere.