Are Interhemispheric Couplings (IHCs) driven differently in the early-winter SSWs compared to the late winters?

The interhemispheric coupling (IHC) is known as the correlation between temperature anomalies in the winter stratosphere and the upper mesosphere of the summer hemisphere. Numerical simulations, as well as observations, have been previously utilized to investigate the mechanism(s) of IHC, and several mechanisms have been proposed, including: (a) The wave forcing of gravity waves originating from the troposphere; (b) Drag from gravity waves originating in the mesosphere; (c) The driving of quasi-2-day wave (Q2DW), and (d) Circulation changes in the stratosphere.
In the current study, we compare the behavior of the IHC during the early-winter Sudden Stratospheric Warming (SSWs) and late-winter SSWs and potentially link to the aforementioned drivers, utilizing 40 years of SD-WACCM-X simulations and 20 years of MLS observation. The aim of this study is to understand if the seasonal-varying background wind structure has an impact on the IHC behavior.