The ionospheric data observed with the Millstone Hill incoherent scatter radar from 1976 to 2006 were analyzed to deduce the Vertical Equivalent Winds (VEW), which are attributed to both the contributions of neutral wind and electric drifts under different conditions. The results suggest that the Millstone VEW show obvious diurnal, solar activity and seasonal variations. During the nighttime, Millstone VEW are mostly upward and strong, while the daytime VEW are relatively weak, even close to zero. This diurnal variation of Millstone VEW behaves similarly under different solar activities and seasons. Under solar low condition, the nighttime upward VEW are stronger than higher solar activity conditions. These characteristics of the diurnal and solar activity variations of Millstone VEW are closely related to the aurorally driven high-latitude circulation cell and ion drag. The equinoctial symmetry appears for the magnitudes and phase tendencies in spring and autumn are similar. The nighttime drift in winter is relatively weaker than that in summer, and this difference tends to be greater with the increasing solar activity, which shows the important effect of aurorally driven circulation on Millstone Hill ionosphere again. The VEW derived by three methods, i.e., by ion line-of-sight velocities of the F region ionization, servo theory and Ref.[1]'s method are compared. The magnitudes and phase tendencies of the VEW derived by different methods are accorded well with each other at nighttime, while there are larger differences during daytime; this is possibly caused by that the servo constant adopted by the latter two methods plays an important role in modulating the daytime VEW, which has been discussed previously.
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