Abstract:To investigate the differences in stratospheric climate changes during various winter months at the end of the 20th century, the daily ERA5 and NCEP/NCAR data was used to study the decadal changes of the stratosphere in terms of polar vortex intensity and planetary wave forcing, with a particular focus on the contributions of wave 1, wave 2, and wave 3. Results found that in December, wave 1 dominated, with an increased upward propagation of wave 1 in the mid-to-high latitude stratosphere and a weakened upward propagation of wave 2 only in the mid latitude stratosphere. In February, wave 2 predominated, with a significant weakening of its upward propagation in the mid-to-high latitude stratosphere and a decrease in the upward propagation of wave 1 only in the polar region low stratosphere. Wave 3 primarily led to a weakening of propagation along low latitude waveguides in December and an enhancement in February. Further study indicated that the changes in planetary wave propagation associated with the polar vortex in the stratosphere. In December, along with the strengthened propagation along polar waveguides, the polar vortex weakened, warmed, and the mean zonal wind decelerated. In February, with the weakened propagation along polar waveguides, the polar vortex strengthened, cooled, and the mean zonal wind accelerated.