MODELING THE EFFECT OF NATURAL TROPICAL OSCILLATIONS ON THE LARGE-SCALE DYNAMICS OF THE POLAR ATMOSPHERE

Abstract

The influence of tropical oscillations on the thermodynamics of the middle and upper atmosphere of high latitudes was studied. A nonlinear model of the general circulation of the middle and upper atmosphere MUAM was used. Four ensemble calculations were carried out (10 runs in each ensemble) for January - February. It was determined that for January and February, the zonal component of the wind and divergence were especially strong under La Niña and the western phase of the QBO (wQBO) conditions. There is also an increase in convergence/divergence zones in the stratosphere of middle and high latitudes. While in January there is a strong convergence in the mid-latitudes at altitudes of 40-60 km for the combination of El Niño and the eastern phase of the QBO (eQBO), there is a strong convergence for El Niño and the wQBO in February. For January and February during La Niña and wQBO conditions the residual mean circulation (RMC) from the summer hemisphere to the winter hemisphere is maximum, which leads to the greatest positive temperature anomaly (up to 10 K) at altitudes of 60-80 km in the latitudinal zone from 55 to 90. However, in January, with El Niño and eQBO, the RMC is the weakest, which leads to a negative temperature anomaly (up to -6…-8 K). The weakest transfer is recorded in El Niño and wQBO conditions in February.