WT5”HZ] F region electron density depletions associated with main ionization troughs in the high latitude ionosphere are studied using EISCAT CP3 data of meridian scanning experiments. The troughs in our observations are found to appear mainly in dusk sector, extending from late afternoon to pre midnight, with higher occurrence rate during equinox and winter. Simultaneous ion drift velocity in F region shows that the main trough minimum is mostly located at the equator ward edge of the plasma convection flow, rather than in the region where the largest ion flow are observed. WT5 "HZ] F region electron density depletions associated with main ionization troughs in the high latitude ionosphere are studied using EISCAT CP3 data of meridian scanning experiments. The troughs in our observations are found to appear mainly in dusk sector, extending from late afternoon to pre midnight, with higher occurrence rate during equinox and winter. Simultaneous ion drift velocity in F region shows that the main trough minimum is mostly located at the equator ward edge of the plasma convection flow, rather than in the region where the largest ion flow are observed .