Model estimates for the sensitivity of atmospheric centers of action to global climate changes

The sensitivity of the characteristics of atmospheric centers of action (ACAs) in the Northern Hemisphere to global climate changes is analyzed on the basis of models of different complexity, including the climate model of intermediate complexity of the Institute of Atmospheric Physics, Russian Academy of Sciences and the ECHAM4/OPYC3 and HadCM3 general circulation models of the atmosphere and ocean. The emphasis is on the analysis of trends of the change in ACA characteristics in winter, when the long-term global warming is most considerable. The global climate models are shown to be able to describe not only the intermediate regimes of ACAs but also their dynamics. In particular, ECHAM4/OPYC3 is capable of reproducing the statistically significant connection of the characteristics of the North Pacific centers of action with El Niño/La Niña events, revealed from observational data. With the use of the results of the global climate models, the possible changes in the characteristics of centers of action in the 21st century are estimated for an increased content of greenhouse gases in the atmosphere.