Variability of F2 parameters depending on MODIP Original Research Article

Using hourly daily data of 15 stations the average quiet-time variability of f0F2 was determined hour by hour and month by month. An approximation of the resulting 24×12 tables by double Fourier analysis up to second order, first by hour and then by month, gave one 5×5 coefficient matrix per station. At low and middle latitudes the model amplitudes (averaged over all months) are found comparable, except for stations near the equatorial crest or at high latitudes where they are greater. With the modified dip coordinate (used by CCIR), they increase from midlatitude toward the auroral zone.