Diurnal Variation of Ionospheric Electron Contena Obtained from Doppler Slopes of Simultaneous Satellite Signals

摘要

All Doppler methods for measuring the electron content using simultaneously emitted rocket or satellite cw signals of different frequencies are based on the assumption that those signals travel towards the observer along nearly identical paths. The data used in this paper is based on the measurement of Doppler slopes of high elevation orbits at the points of inflection. The comparison of the observed time moments at which Doppler inflection of different frequencies occurs provides a means of selecting only those data that are actually simultaneous. Data selected in accordance with this principle can be evaluated on the basis of straight-line propagation. The actual data describe the diurnal variation of the integrated electron density during November-December 1961. Attention is focused on an apparent enhancement of the content about mid-night. This enhancement is considered to be indicative of vertical downward electron transport.