Low‐Latitude Ionospheric Electron Content Measurements During Half a Solar Cycle

Abstract
This paper presents the results of total electron content measurements made at São José dos Campos (23.22°S, 45.98°W) between 1963 and 1968. The 1963 measurements were made by using the differential Doppler shift technique, and from December 1964 onwards the close‐spaced‐frequency method was employed using the 40 and 41 MHz transmission from the BE‐B and BE‐C satellites. An analysis is made of the variation of electron content with local time, dip angle, season, solar activity, and magnetic activity. Special attention is given to the equatorial anomaly and the region of the Brazilian magnetic anomaly.