Diversity of microenvironments and the complexity of vortex motion

The complexity of major vortex motion in a system where four scales are coexisting (a subtropical high ridge, the major vortex, meso‐ and small‐scale vortices) is examined numerically using a barotropic primitive equation model. The microenvironment of a major vortex consists of a group of small‐scale vortices in which varying values for the total number N of initial small‐scale vortices (N = 2, 3, 4, and 5, respectively) creates a diverse range of microenvironments. Three kinds of major vortex motion are observed: (i) the initial major vortex decays away with no new major vortex formation; (ii) a weak new major vortex forms while the major vortex decays; and (iii) a new major vortex occurs, via self‐organization, with its intensity and scale similar to those in the initial stages of the original major vortex, and this vortex continues to shift westwards after the old major vortex decays.