[P-EM05_2AM1] Characteristics of atmospheric waves in the mesosphere-lower thermosphere (MLT)

[PEM05-03] Behavior of non-migrating tides in the MLT region

*Yasunobu MIYOSHI¹, Hitoshi FUJIWARA² (1.Kyushu University, 2.Seikei University)

Keywords:Tides, General Circulation Model

It is well established that non-migrating tides have significant amplitudes in the mesosphere and lower thermosphere (MLT). Using a general circulation model that contain the region from the ground surface to the upper thermosphere, behavior and excitation sources of non-migrating tides are examined. In this study, behaviors of the westward moving semidiurnal tide with zonal wavenumber 1 (SW1), the semidiurnal tide with zonal wavenumber 0 (S0) and the diurnal tide wit zonal wavenumber 0 (D0) are examined in detail. There are two main sources for non-migrating tides. One is latent heat release due to the cumulus convection in the troposphere. The other is the nonlinear interaction between the migrating tide and the stationary planetary wave in the middle atmosphere. Our results indicate that the amplitudes of SW1, S0 and D0 are enhanced when the stationary planetary wave in the stratosphere and mesosphere is active. This means that SW1, S0 and D0 are mainly excited by the nonlinear interaction between the migrating tide and the stationary planetary wave. Furthermore, we discuss excitation sources of other non-migrating tides, such as the eastward moving diurnal tide with zonal wavenumber 3 (DE3) and the eastward moving semidiurnal tide with zonal wave number 2 (SE2).