General circulation of the atmosphere that is driven thermally and dynamically exhibits fascinating patterns. I am interested in studying changes of the general circulation on the climate time scales. These changes may arise from anthropogenic external forcings to the climate system, and/or from internal couplings whitin the system. I am particularly interested in the region of upper troposphere and lower stratosphere, where dynamical, radiative, chemical and thermodyanmical processes are tightly coupled. Using the state-of-the-art atmospheric model developed at the Geophysical Fluid Dynamics Laboratory, together with the latest observations, I am seeking to an improved understanding of the climate system on the process level.