Effect of the Madden–Julian Oscillation and Quasi-Biennial Oscillation on the Dynamics of Extratropical Stratosphere

Abstract

The effects of the Madden–Julian oscillation and quasi-biennial oscillation in the equatorial stratosphere on the dynamic processes in the extratropical stratosphere has been studied with the use of a model of the middle and upper atmospheric circulation. The heat source of the Madden–Julian oscillation in tropics is specified as a longitude-modulated wave perturbation with a zonal wavenumber of m = 2 and a period of about Т = 45 days that propagates eastward with a phase speed of ~5 m/s. Ensemble calculations were carried out independently for the westerly and easterly phases of the quasi-biennial oscillation. Analysis of the results has shown that both phenomena strongly affect the circulation of the winter extratropical stratosphere, the polar vortex decay, and sudden stratospheric warming events; the character of the effect depends on the combination of their phases. The good agreement between the simulation results and the reanalysis of data confirms our results.