Fig. 4From: Characteristics and longitudinal extent of VLF quasi-periodic emissions using multi-point ground-based observations10-min plot wave spectra on 21 December 2017. Wave spectra at (top) KAN and (bottom) IST detected on 21 December 2017 from 19:30 to 19:40 UT showing two QP emissions with one-to-one correspondence at the two locationsBack to article page