Day-to-day variations of migrating semidiurnal tide simulated by a general circulation model

By using a general circulation model, we examine behavior of the migrating semidiurnal tide for equinox during solar cycle minimum and geomagnetically quiet conditions. We investigate day-to-day variations of the migrating semidiurnal tide in the mesosphere and thermosphere, and their relation with the migrating semidiurnal tide generated in the lower atmosphere. The results show that day-to-day variations of the migrating semidiurnal tide are evident from the upper troposphere to the thermosphere. Fluctuations of the migrating semidiurnal tide amplitude with periods of 17-18 and 25 days are found at altitudes from 20 to 200 km height, indicating dynamical coupling between the mesosphere and thermosphere and the lower atmosphere.