Ionospheric drift measurements are of significant importance in the monitoring of the upper atmosphere dynamics and an important contributor toward the deeper understanding of the ionospheric electrodynamics. An interesting perspective for operational ionospheric drift measurements comes from the HF radars, such as the Digisondes. Nevertheless, when interpreting velocity measurements obtained from the Digisonde drift analysis method, care must be taken in relating the motion to the effects of photoionization, recombination, gravity waves, and plasma motion. In this paper we investigate the effect of all different mechanisms contributing to the apparent velocity measured by the Athens Digisonde. As a first step, the daily drift pattern over Athens under quiet magnetospheric conditions is preliminarily determined for the equinox months. Moreover, the substorm effect on the extracted pattern is also investigated. Our results provide some evidence for the direct effect of traveling atmospheric disturbances in the vertical component, while in the horizontal plane, the disturbance could be attributed to other substorm-related mechanisms.