Studies of the auroral E region neutral solar cycle: Quiet days

On the basis of the data obtained by the European Incoherent Scatter radar located in northern Scandinavia, we have studied E region neutral wind char acteristics between 95 and 119 km under geomagnetic quiet conditions (Ap < 16) over a solar cycle between November 1986 and October 1996. Data of 56 d ays were analyzed and grouped in order to investigate variations of;the win d in different seasons and solar cycle conditions. Seasonal and solar cycle dependences of mean winds as well as diurnal and semidiurnal amplitudes ar e found. Phase differences of the diurnal and semidiurnal components are le ss than 2 hours between different season and solar activity conditions. No prominent seasonal nor solar cycle dependence is found for the vertical com ponent. Comparisons are made with model predictions and radar observations as well as UARS observations in terms of seasonal and solar cycle dependenc es of the wind. Possible roles of gravity waves are discussed in terms of t he seasonal variation of zonal mean wind.