Amplification of the influence of solar flux variations on the winter stratosphere by planetary waves

Recent observational evidence has suggested that variations in solar activi ty may affect winter stratospheric polar ozone and temperature levels. The paucity of direct sunlight available during this season points strongly to a dynamical mechanism. We have carried out several large ensemble experimen ts within the middle atmosphere and the coupled middle atmosphere and lower thermosphere to simulate the radiative/dynamical coupling via planetary wa ves for a range of solar fluxes. In the former case, the model response in the winter stratosphere was linear and of the order of the summer stratopau se forcing, whilst in the latter, the level of correlation in the winter st ratosphere remained high, but was diluted over a wider volume. The inclusio n of the upper atmosphere enhanced the winter polar stratospheric response by a factor of three.