Theory of three-pattern decomposition of global atmospheric circulation

This paper reviews the three-pattern decomposition of global atmospheric circulation (3P-DGAC) developed in recent years, including the decomposition model and the dynamical equations of global horizontal, meridional, and zonal circulations. Compared with the traditional two-dimensional (2D) circulation decomposition method, the 3P-DGAC can effectively decompose the actual vertical vorticity into two components that are caused by the horizontal circulation and convergent/divergent movement (associated with the meridional and zonal circulations). It also decomposes the vertical velocity into the components of the meridional vertical circulation and the zonal vertical circulation, thus providing a new method to study the dynamical influences of convergent/divergent motions on the evolution of actual vertical vorticity and an accurate description of local vertical circulations. The 3P-DGAC is a three-dimensional (3D) circulation decomposition method based on the main characteristics of the actual atmospheric movements. The horizontal, meridional, and zonal circulations after the 3P-DGAC are the global generalization of Rossby waves in the middle-high latitudes and Hadley and Walker circulations in low latitudes. Therefore, the three-pattern decomposition model and its dynamical equations provide novel theoretical tools for studying complex interactions between middle-high and low latitude circulations as well as the physical mechanisms of the abnormal evolution of large-scale atmospheric circulations under the background of global warming.