Longitudinal characteristics of spreadFbackscatter plumes observed with the EAR and Sanya VHF radar in Southeast Asia

摘要: [1] The development of equatorial plasma irregularity plumes can be well recorded by steerable backscatter radars operated at and off the magnetic equator due to fact that vertically extended plume structures are tracers magnetically north-south aligned larger scale structures. From observations during March 2012, using two low latitude in Southeast Asia, Equatorial Atmosphere Radar (EAR) (0.2°S, 100.3°E; dip lat 10.4°S) Sanya VHF radar (18.4°N, 109.6°E; 12.8°N), characteristics over sites separated longitude ~1000 km were simultaneously investigated. The beam steering measurements reveal frequent occurrences multiple both sites, which cases analyzed here. on 30 2012 show initiated within scanned area, followed others drifting from west stations. A tracing analysis onset locations reveals spatially well-separated plumes, with a maximum east-west wavelength about 1000 km, periodically generated longitudes between 85°E 110°E. postsunset seen found passage sunset around EAR. Most interestingly, EAR night 21 developed successively area separation ~50 however no Sanya. Colocated ionogram spread F irregularities occurred mainly bottomside region Sanya, whereas satellite traces ionograms indications large-scale wave observed Possible causes for longitudinal difference discussed.