The Solar Cycle and the F2Region of the Ionosphere

This paper presents a method of analyzing F2-region critical-frequency data in a way that shows in a clear-cut manner the correlation that exists between monthly average values of these critical frequencies for undisturbed days and solar activity as measured by the central-zone character figures for calcium flocculi. Curves are presented which show for each month the expected diurnal variation of f0f2 for two values of solar activity. Other curves show for a number of different hours the expected seasonal variation of f0F2 at a constant time of day for the same values of solar activity.