Comparison of variously derived solar indexes

Abstract

Relative merits of ionospheric solar indexes, obtained from (A) 27‐day and monthly median values of ƒ°F2, and (B) ƒ°ƒ2 from one representative ionospheric station and from an average of three such stations, were tested by the following criteria: (i) Magnitude of their standard deviations from their running mean, and (ii) degree of correlation with ƒ°ƒ2 from other stations. No significant difference was found between the merits of solar indexes derived from 27‐day or monthly medians of ƒ°ƒ2. Those derived from a three‐station average were slightly better than those obtained from ƒ°ƒ2 for a single station (Washington, D.C.).