Modeling Residual Meridional Circulation at Different Phases of the Quasi-Biennial Oscillation

The sensitivity of the residual meridional circulation (RMC) in the middle and upper atmosphere to the phase change of the quasi-biennial oscillation (QBO) of the low-latitude zonal wind in the stratosphere has been studied. Wind and temperature data obtained from a nonlinear numerical model of general circulation of the middle and upper atmosphere (MUAM) have been used to calculate the RMC. For the first time, statistically significant results have been obtained illustrating the change in wave-induced eddy flows in the extratropical strato–mesosphere at different QBO phases. Specifically, a general weakening of the eddy circulation in the Northern Hemisphere at the westerly QBO phase has been demonstrated, with the exception of the region located at midlatitudes in the altitude range of 50–60 km. The study of the RMC sensitivity to changes in QBO phases helps better understand the features of the dynamic interaction between tropical and extratropical latitudes, as well as different atmospheric layers that affect the circulation transport and mixing of long-lived atmospheric components.