Fig. 5From: Lightning-associated VLF perturbations observed at low latitude: Occurrence and scattering characteristics(a)–(b): Early/slow events observed on NPM signal. Solid traces (blue color) and dotted traces (red color) represent amplitude and the phase, respectively. The spectrogram in middle gives the tweek sferics associated with causative lightning for event (a). The vertical dashed line in panel b) indicates the time of lightnings detected by WWLLN.Back to article page