New insights into the polar ozone and water vapor, radiative effects, and their connection to the tides in the mesosphere–lower thermosphere during major sudden stratospheric warming events

<p dir="ltr">We examine the variability of diurnal tide (DT), semidiurnal tide (SDT), and terdiurnal tide (TDT) 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), as well as one station outside the polar vortex located at Collm (51.3° N, 13° 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 latitudes. We use short-wave (QRS) and long-wave (QRL) radiative heating and cooling rates simulated by the WACCM-X(SD) model to investigate the roles of polar ozone and water vapor in driving 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 in zonal and meridional components is observed, with a decrease of 3 m s−1, approximately 25 % change compared to the mean TDT amplitude. Meanwhile, SDT shows a positive anomaly of 10 m s−1, with changes reaching up to 40 %, indicating an enhancement of tidal amplitude in both components. The DT amplitude exhibits a delayed enhancement, with a positive amplitude anomaly of up to 5 m s−1 in the meridional wind component, occurring approximately 20 d 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 changes but appears to be important 20 d after the event, particularly during 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. This study presents the first comprehensive analysis of mesospheric tidal variability in polar regions during sudden stratospheric warmings (SSWs), examining and linking the significant role of trace gases and radiative effects in modulating tidal dynamics.</p>