Results derived from simultaneous measurements using the Langmuir plate and spherical ion probe on explorer XXXI and the ionosonde on Alouette II

Measurements of electron temperature, ion concentration, and ion temperature obtained by means of the Langmuir plate and spherical ion probe on the Explorer XXXI satellite are presented together with results obtained at the same time from the Alouette II ionosonde for a period when the two satellites were close together. Electron concentration measurements by the sounder have been used for in-flight calibration of the probe total positive ion concentration measurements, and an effective grid transparency for the probe was obtained. This transparency, which appears to be different for different ion species, was 35 percent for hydrogen ions and 42 percent for oxygen ions. Results from a set of measurements centered on a latitude near 70° magnetic dip in the Australasian region are tabulated and have been used to determine vertical temperature gradients of the plasma on the basis of diffusive equilibrium theory. The calculated gradients are negative between altitudes of 650 and 1050 km. The reality of these negative gradients cannot be confirmed because the direct measurements of plasma temperature exhibit large day-to-day fluctuations so that a reliable height variation of temperature cannot be constructed.