Influence of atmospheric variations in the polar stratosphere of the southern hemisphere during 2002–2022 on polar planetary wave activity

Abstract. Atmospheric planetary waves has long been studied, focusing on the equator and the middle and low latitudes. However, variation of polar planetary wave activity, especially temperature, temporal, and interannual variations of polar planetary waves, remain largely unexplored. In this study, we use MERRA-2 dataset to investigate the impact of atmospheric variations on polar planetary waves there during austral winter from 2002 to 2022. The temperature amplitude and wave periods of each polar planetary wave event were determined using 2-D least-squares fitting. Our results show that, as the zonal wavenumber increases, E1, E2, E3, and E4 occur earlier with weaker peak amplitudes and shorter wave periods. The phase velocities of E1, E2, E3 and E4 are similar to ~40 m/s in the polar atmosphere. In order to elucidate the variations in the observed polar planetary waves and its possible propagation and amplification mechanism, we carry out the diagnostic analyses with MERRA-2 reanalysis data from the surface up to ∼ 80 km. Results indicate that the polar planetary waves can be amplified in instability of the mesosphere ~50–60° S and the stratosphere ~70–80° S. The mean flow instability of the strong polar planetary wave during the austral winter mesosphere is greater than that of the weak wave. The selective generation, propagation, and amplification of planetary waves with varying zonal wavenumbers due to variations in background zonal winds in the polar atmosphere. The temperature amplitude of polar planetary wave correlates with solar activity F10.7. The correlation between zonal wavenumber, wave period, and phase velocity implies that polar planetary waves propagate as fixed-phase wave packets. These results can suggest that, the background atmospheric conditions in the polar regions play a crucial role in modulating the generation, propagation, and amplification of planetary waves. Overall, we analyze their dynamics variation of eastward planetary waves in the polar atmosphere during the 2002–2022 austral winter periods and statistically analyze the interannual variation.