Fig. 12From: A confirmation of vertical acoustic resonance and field-aligned current generation just after the 2022 Hunga Tonga Hunga Ha’apai volcanic eruptionHarmonic structure of the PSD in 05:15–05:32 UT when a sawtooth waveform is observed (upper panel). Higher harmonics of the fundamental period around 265 s (256 s in this plot because of FFT algorism) is seen. The lower panel shows the phase of each frequency componentBack to article page