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5.Concluding remarks

Throughout the present analysis of the NCEP/NCAR data over 20 years, some characteristic features of the interannual variations of the wintertime SH stratosphere and their connection with the tropospheric dynamics are found. They are summarized as follows:

i. The year-to-year variation of monthly mean planetary waves at 10hPa can be characterized by the east-west drift of the phase, as well as by the intensity of the wave amplitude.
ii. The variation of stratospheric wave pattern is well correlated with that of tropospheric circulations, in such a way as the phase with the upper tropospheric jet structure and the amplitude with the heat flux pattern.
iii. The result of SVD analysis for the stratospheric planetary wave and the tropospheric heat flux confirms that their year-to-year variations are tightly connected each other.

All of these results strongly suggest that the generation and maintenance of SH stratospheric waves are quite sensitive to the transient wave activity in the troposphere. In this regard, the generation mechanism for the SH stratospheric wave by the forcing below should be further investigated, as well as the nature of interannual variabilities in the troposphere.