Solar control of the amplitude and phase of the yearly mean Sq( H) at Alibag for the period 1905 to 1960

Abstract

The yearly mean diurnal variation of H at Alibag for the international quiet days is obtained for each of the years 1905–1960 and the first two harmonics of the variation derived by Fourier analysis. A study of the amplitudes and times of maximum of the first and second harmonics with respect to solar activity shows that (i) the amplitudes of both the harmonics have a good direct correspondence with sunspot numbers. (1) the maximum of the first harmonic occurs at a later time with increasing solar activity, while the time of maximum of the second harmonic shows no systematic relationship with sunspot number. The correspondence between the amplitudes and sunspot number should be the direct consequence of the increase with solar activity of the ionization intensity and therefore the conductivity of the E-region. The lag in the time of maximum of the first harmonic with increasing sunspot number appears to be connected with the relaxation time of the E-region, though no definite conclusions can be arrived at for want of sufficient data regarding the coefficient of recombination for E-layer heights.