Variations of migrating and non-migrating tides simulated by the Middle Atmosphere Circulation Model at Kyushu University

Atmospheric diurnal and semidiurnal tides simulated by the Middle Atmosphere Circulation Model at Kyushu University (MACMKU) for equinox conditions are analyzed to investigate behavior of non-migrating tides. It is shown that the model non-migrating diurnal and semidiurnal tides have nonnegligible amplitudes in the upper mesosphere and lower thermosphere, with the amplitudes and phases of the non-migrating tides more variable than those of the migrating tides. EP-fluxes are also analyzed to infer the generation mechanism of the non-migrating tides. It is found that the EP-flux associated with the non-migrating tide having larger zonal wavenumber shows more systematic upward propagation from the troposphere than that associated with the smaller zonal wavenumber components, implying that the form is generated in the troposphere while the latter is generated in the mesosphere. (C) 1999 COSPAR. Published by Elsevier Science Ltd.