On the location of the effective equator for theFregion of the ionosphere

A method capable of precisely defining the position of the effective equator is outlined. The method is applied to the analysis of the noon values of ƒoF2 and post sunset h′F peak during the equinoctial months, March and September 1958. It is found that in the latitude zone of 40° to 70° only the dipole latitude has significant control on ƒoF2, whereas in the equatorial zone only the dip equator controls ƒoF2 significantly. The data analyzed showed minimum ƒoF2 at the dip equator in the African and American sectors; lack of southern stations in the Asian sector makes a definite statement about this region difficult. The analysis of the postsunset h′F peak reveals a dual control of equal weight by the dip equator and the dipole equator. The effective equator for this parameter and anomaly is therefore halfway between the dipole and the dip equators and is termed the mean magnetic equator. The h′F data analyzed showed a maximum at the mean magnetic equator in all sectors of the earth.