Fig. 7From: Monitoring of equatorial plasma bubbles using aeronautical navigation system: a feasibility studyObservation of VHF radio observation in Okinawa on Oct 31 (a, b), and November 1 (c, d), 2021. The upper panels (a, c) are the dynamic spectra of received signal intensity in the aeronautical navigation band from 108 to 118Â MHz, while the lower panels (b, d) are those in the broadcasting band from 98 to 108Â MHzBack to article page