Small Scale Irregularities in Ionospeheric Electron Content

Abstract

This thesis describes a study of the amplitude fluctuations (called scintillation) which are often observed on VHF transmission received from orbiting satellites. Scintillation is usually attributed to small scale irregularities in the ionospheric electron density. The main purpose has been to establish the morphology of the ionospheric irregularities near sunspot minimum, making use of satellite observations between 20°S and 80°S geomagnetic latitude. The scintillation observations are also related to occurrences of spread-F and sporadic-E on ionograms, magnetic activity, auroral phenomena, the solar wind, and the interplanetary magnetic field. Results are used to study the causes of irregularities.