Abstract Using meteor radar observations and reanalysis data, we investigate the variations of the 12.42‐hr oscillations in the mesosphere and lower thermosphere (MLT) region over Yinchuan (YC, 38.8°N, 106.8°E) during four Arctic winters from 2020 to 2024. By comparing the observed oscillation signatures with the evolution of sudden stratospheric warming events, polar vortex weakening (PVW) events, quasi‐biennial oscillation (QBO) phases, and nonlinear wave interactions, we identified distinct mechanisms governing 12.42‐hr oscillation amplification at different altitudes. Below 90 km, the enhancement of the 12.42‐hr oscillation is primarily attributed to nonlinear interactions between the solar semidiurnal tide and quasi‐16‐day waves. Above 90 km, however, the observed enhancements correspond to the lunar semidiurnal tide (LSD) and exhibit a strong dependence on the intensity of PVW events. Although QBO‐related modulation can influence the oscillation, it is not a consistently dominant factor in the upper MLT region, where the oscillation strength more closely follows the variability of PVW events. These findings highlight two distinct physical pathways shaping the 12.42‐hr oscillations in the MLT region: nonlinear wave‐wave coupling below 90 km and polar vortex‐controlled modulation of the LSD above 90 km. This study provides new insights into the dynamical processes governing tidal variability during Arctic winters.
Gong et al. (Tue,) studied this question.