Unexpected Decrease in TW3 Amplitude During Antarctic Sudden Stratospheric Warming Events as Revealed by SD‐WACCM‐X

The specified dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (SD‐WACCM‐X) was utilized to explore migrating tidal variabilities that occurred during the 2002, 2010, and 2019 Antarctic sudden stratospheric warming (SSW) events. All migrating tides show prominent day‐to‐day variations in the mesosphere and lower thermosphere regions, which can be mainly attributed to each Antarctic SSW event. The westward propagating diurnal tide with zonal wavenumber 1 (DW1) and the westward propagating semidiurnal tide with zonal wavenumber 2 (SW2) show a distinct reduction and an increase during each Antarctic SSW event, respectively. Specifically, the westward propagating terdiurnal tide with zonal wavenumber 3 (TW3) shows an unexpected decrease, which is opposite to the behaviors of TW3 reported during Arctic SSW events. We conclude that the unexpected decrease in TW3 may be mainly caused by the nonlinear interaction between DW1 and SW2, in which DW1 may play a major role. In the ionosphere, the TW3 amplitudes also show a decrease during each Antarctic SSW event, which is in consistency with decreasing tidal amplitudes in the neutral atmosphere. Our study demonstrates that TW3 is also a considerable source for short‐term ionospheric variability during Antarctic SSW events. Key Points TW3 amplitudes show an unexpected decrease in the neutral atmosphere during Antarctic sudden stratospheric warming (SSW) events as revealed by SD‐WACCM‐X The decrease in TW3 is likely due to the weakness of DW1 and derived from nonlinear wave‐wave interactions The simultaneous decrease in the TW3 amplitudes in the ionosphere indicates neutral‐ion coupling through tides during Antarctic SSW events