Interannual variations in the total ozone, stratospheric dynamics, extratropical SST anomalies and predictions of abnormal winters in Eurasia
Abstract:Analysis of the monthly mean interannual variations in the total ozone (TO), zonal stratospheric circulation, three-dimensional Eliassen-Palm (EP) fluxes and their correlations with the surface air temperature (SAT) and sea surface temperature (SST) anomalies in the North Pacific and North Atlantic was carried out. Interannual TO variations are strongly connected with those of the zonal wind in the lower stratosphere during the winter. A strong upward propagation of planetary waves from the troposphere to the stratosphere over northern Eurasia and a weak downward propagation in Labrador and South Greenland regions are indicated. There are large differences in the interaction of the zonal mean circulation and wave processes between early winter (November-December) and mid-to-late winter (January-March). Amplification of the penetration into the stratosphere of planetary waves in December is strongly associated with changes in the stratospheric dynamics in January, creating the 'preconditions' for the appearance of stratospheric warming. We show that the 'stratospheric bridge', with a strengthening of the downward propagation of the vertical EP flux over the North Atlantic, is being formed for years with a strong polar vortex. Simultaneous correlations of the stratospheric circulation variations with the Southern Oscillation Index show its small linkage with the stratospheric dynamics in the Arctic. However, there are significant correlations of the extratropical SST anomalies in the North Pacific and the North Atlantic with the interannual variations in the stratospheric dynamics. We demonstrate that the TO changes over the UK in January can be a good predictor of the anomalous cold/warm winters in distinct regions of Eurasia in February. The TO and other stratospheric predictors can be used for extended-range forecasting of extreme winters in Eurasia. Possible mechanisms for stratosphere-troposphere coupling and its link to the extratropical SST anomalies are discussed.
Document Type: Research Article
Affiliations: P. P. Shirshov Institute of Oceanology, 36 Nakhimovsky Ave., Moscow, Russia
Publication date: April 1, 2010