Abstract
The generation of the mean zonal wind in the lower thermosphere is discussed, based upon momentum transport by dissipating tidal waves, especially, the first mode of the solar diurnal tide (S11) and the second symmetric mode of the solar semidiurnal tide (S42). The amplitudes of tidal waves at the lower boundary are set to reasonable values which are obtained by the observations and the theoretical studies. The problem is solved numerically as the initial value problem as done by Miyahara (1978). It is shown that these dissipating tidal waves, especially, S11 mode can induce strong easterly (-66m/sec) in the lower thermosphere over the equator.