SOLAR-CYCLE VARIATION OF THE DAILY FOF2 AND M(3000)F2

Daily values of the ionospheric characteristics fo F2 and M(3000)F2 fo r a given hour and month are correlated with the corresponding daily v alues of sunspot number using measured data collected at seven Europea n locations. The significance of applying different-order polynomials is considered and the times are confirmed when the higher-order terms are important. Mean correlation coefficients for combined data sets ov er all hours, months and stations are determined, together with the st andard errors of estimates. Comparisons are made with corresponding fi gures for monthly median values derived from the same data sets.