Response of the Tropospheric Dynamics to Extreme States of the Stratospheric Polar Vortex during ENSO Phases in Idealized Model Experiments

Abstract

Extreme states of the stratospheric polar vortex (SPV) affect the average position of the main propagation trajectories of synoptic vortices in the Northern Hemisphere over a time period from 2 weeks to 2 months. This time scale is considered one of the most difficult periods in forecasting. Based on the analysis of data from idealized numerical experiments on the Isca platform, we have studied the processes of formation of anomalous positions of storm tracks in the Atlantic–European region as a response to sudden stratospheric warmings (SSWs) and events of extremely strong SPV during various phases of the El Niño Southern Oscillation (ENSO). It is shown that in winter it is impossible to unambiguously talk about the southward displacement of the Atlantic storm track during El Niño events without taking into account the intensity of SPV. The intensity of SPV, expressed as the zonal component of wind speed, averaged along 60° N at the level of 10 hPa, has its maximum predictive potential during El Niño.