Covariation of critical frequency of F2-layer and relative sunspot number

Abstract

Seasonal and overall covariation of relative sunspot number and the critical frequency of F2-layer of the terrestrial ionosphere has been investigated and the following results have been obtained; 1) There is a strong correlation between the relative sunspot number and the critical frequency of F2-layer of ionosphere. 2) There exist alternate similar and dissimilar zones in the seasonal variation pattern of the relative sunspot number and critical frequency of F2-layer. 3) Critical frequency of F2-layer increases nonlinearly with relative sunspot number reaching a maximum at sunspot maximum. 4) An empirical equation connecting critical frequency of F2-layer with relative sunspot number has been derived by applying least square method of curve fitting which gives values of critical frequency of F2-layer very close to the experimentally obtained values of the same.