Preliminary comparisons of VHF radar maps of F-region irregularities with scintillations in the equatorial region

Multiantenna 50 MHz radar backscatter maps of echo power from night-time F-region equatiorial irregularities obtained at Jicamarca, Peru were compared with simultaneous VHF scintillation observations from Huancayo at 137 and 254 MHz during the period 20 November to 12 December 1975. Saturation of VHF scintillations in excess of 20 dB was observed at both these frequencies during times when radar maps showed large intense plume structures rising into the topside ionosphere. On nights when only thin layers of bottomside irregularities were observed, moderate to weak scintillations were recorded at VHF. Preliminary values of east-west horizontal irregularity drift velocities were obtained and compared with scintillation rate observations. Using the 1.5-deg and 4.5-deg longitudinal separation between the Jicamarca radar and ionospheric observation points of the two satellites from Huancayo, information was derived regarding large-scale east-west structure during the development phase of the irregularities.