Numerical simulation of sensitivity of meridional circulation to impacts of orographic gravity waves and QBO phases in the middle and upper atmosphere: A. V. Koval, N. M. Gavrilov, А. I. Pogoreltsev, and E. N. Savenkova

Conclusion. In this study, we performed numerical experiments with the
MUAM model simulating the general circulation in the middle atmosphere using ten-year average meteorological information. We focused on the sensitivity of the meridional and vertical circulation in the middle and upper atmosphere to inclusion of recently developed parameterization of OGW dynamical and thermal effects for the initial and boundary conditions typical for the easterly and westerly QBO phases. The main goal was to understand the role of the processes associated with dynamical coupling between different atmospheric layers in general circulation model. Results of numerical experiments show that global-scale meridional and vertical circulation in the MUAM model is very sensitive to OGW dynamical and
thermal effects, as well as to the changes in QBO phase. Changes in meridional velocity in the middle atmosphere can reach +/- (30—40)% at high latitudes of the northern hemisphere. In the years with QBO easterly and westerly phases, the differences in meridional velocities can reach 60% at altitudes of 40—60 km. The corresponding changes in vertical velocities can reach 20—50% in the Northern Hemisphere at altitudes of 10—40 km. In addition to directly influencing dynamic and thermal processes in the atmosphere, changes in circulation at these altitudes can lead to changes in ozone fluxes, significantly changing its concentration. OGW effects and changes in QBO phases, can have a
similar effect on meridional circulation in the middle atmosphere, despite the different physical mechanisms.