Numerical simulation of the 5-day and 16-day waves in the mesopause region

The behavior of the 5-day and 16-day waves in the mesopause region is examined by using a general circulation model. The results are as follows. The 5-day wave is largely unaffected by the zonal mean zonal wind distribution, and the symmetric structure about the equator is clearly seen in the mesopause region. The amplitude of the 16-day wave in the summer hemisphere of the stratosphere is small. However, above the upper mesosphere, the 16-day wave appears not only in the winter hemisphere but also in the summer hemisphere. The penetration of the 16-day wave from the winter hemisphere to the summer hemisphere occurs near the mesopause region. The 16-day wave is mainly excited by heating due to the moist convection in the troposphere, and the vertical penetration into the middle atmosphere occurs. Furthermore, a correlation between the geomagnetic variation and the wind variation associated with the 5-day and 16-day waves is discussed.