Some regularities in theF2 region of the ionosphere

Abstract

A quick and approximate method was used to analyse (h′ - f) records of radio waves reflected from the ionosphere so as to give the total number (n) of electrons below the level of maximum electron density in a column of unit cross-section in the F2 region. The, analysis was carried out on records obtained at Watheroo (Australia), Huancayo (Peru), and College (Alaska) for two magnetically quiet days per month in a year of sunspot maximum and a year of sunspot minimum. It was found that the quantity n was closely related to the zenith angle (χ) of the sun's rays, whereas it is well known that the maximum electron density Nm in the F2 layer is not simply related to this angle. The well-known anomalies which are apparent when Nm is studied as a function of time of day, time of the year, and geographical position, all seemed to disappear when the quantity n was studied instead. A new kind of anomaly which was observed at Huancayo in years of sunspot minimum is described and discussed. A relation between the thickness and the height of the F2 layer is established and the possibility of using it in ionospheric forecasting and theory is discussed. Since the deductions of this paper are made on data from only three stations, it is suggested that a similar analysis should be made for other stations. This is all the more necessary because two other sets of workers have reported results in disagreement with those obtained in this paper.