Generation of kilometer scale irregularities during the midnight collapse at Arecibo

摘要: Coordinated observations of the incoherent scatter radar at Arecibo, Puerto Rico, and total electron content/scintillation measurements made by using 137-MHz transmissions from geostationary satellite SMS 1 nearby station Ramey are studied to determine background ionospheric conditions necessary for generation kilometer scale irregularities in midlatitude ionosphere. It is found that well-known midnight descent or collapse F region known occur this part world sometimes associated with increases bottomside content, as well large scintillation events (∼10 dB). From a measurement vector ion velocities densities during such events, it determined scintillations eastward northward electric fields coupled directed density gradient caused propagation collapse. The role possible plasma instability mechanisms, specifically E × B drift Perkins instability, discussed formation giving rise VHF scintillations.