It is possible to deduce F region ionization motions from Sq current distribution maps, but is known that the agreement between the deduced velocities and the experimentally observed velocities is poor. In order to determine whether the disagreement between the deduced and the observed results is a result of the uncertainty in the location of the zero value of the current the velocities were deduced from an Sq map with the daily mean values as the base line and from an Sq map with the midnight values as the base line. Th disagreement betwen the deduced and the observed velocities in both cases indicates the importance of polarization fields in ionosphric motions.