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Abstract:
We examine the variability of diurnal (DT), semidiurnal (SDT), and terdiurnal (TDT) tide amplitudes in the Arctic mesosphere and lower thermosphere (MLT) during and after sudden stratospheric warming (SSW) events using meteor radar data at three polar-latitude stations: Sodankylä (67.37° N, 26.63° E), Tromsø (69.58° N, 19.22° E), and Svalbard (78.99° N, 15.99° E). By combining tidal amplitude anomalies with trace gas variations, induced by large-scale dynamical changes caused by the breaking of planetary waves, this study provides new observational insights into the variation of ozone and water vapor, transport, and tides at polar latitude. We use short-wave (QRS) and long-wave (QRL) radiative heating and cooling rates simulated by the WACCM-X model to investigate the roles of polar ozone and water vapor in linking mesospheric tidal variability during SSWs in the polar regions. Our analysis reveals distinct tidal responses during SSW events. At the onset of SSWs, a significant negative anomaly in TDT amplitudes is observed, with a decrease of 3–4 m/s, approximately 15–20 % change compared to mean TDT tide. Meanwhile, SDT shows a positive anomaly of 10 m/s, with changes reaching up to 40 %, indicating an enhancement of tidal amplitude. The DT amplitude exhibits a delayed enhancement, with a positive amplitude anomaly of up to 5 m/s in the meridional wind component, occurring approximately 20 days after the onset of SSWs. A similar, but weaker effect is observed in the zonal wind component, with changes reaching up to 30 % in the zonal component and 50 % in the meridional wind component. We analyzed the contributions of ozone and water vapor to the short-wave heating and long-wave cooling before, during, and after the onset of SSW events. Our findings suggest that the immediate responses of SDT are most likely driven by dynamical effects accompanied by the radiative effects from ozone. Radiative forcing change during SSW likely plays a secondary role in DT tidal changes but appears to be important 20 days after the event towards the spring transition. Water vapor acts as a dynamical tracer in the stratosphere and mesosphere but has minimal radiative forcing, resulting in a negligible impact on tidal changes. The interaction between dynamic processes and the transport of radiatively active gases is important for explaining the observed tidal variability during SSW events. This study provides the first comprehensive analysis of mesospheric tidal variability in polar regions during SSWs, exploring and linking the significant role of trace gases and radiative effects in modulating tidal dynamics.
