INTERACTION OF 2 BAROTROPIC GAUSSIAN VORT ICES OF DIFFERENT SCALES - NUMERICAL EXPERIMENTS

The travel of an intense vortex in the field of another vortex larger in size is studied numerically. The evolution of the small vortex is d etermined by three basic factors: the velocity field induced by the la rge vortex, the velocity shear, and the gradient of the potential vort icity of the ambient flow (beta effect). The action of the first two f actors results in the fact that the small vortex is drifted by the amb ient flow and deformed. The third factor leads to the fact that a vort ex of the same sense as that of the large vortex moves to its center a nd a vortex of the opposite sense is drifted to the periphery. Calcula tions were performed at different amplitudes of the large vortex. In a ll the cases, the small cyclonic vortex was moving in a spiral toward the center of the large vortex due to the presence of a potential vort icity gradient of the latter. This is a possible mechanism of the merg er of two vortices of the same sense and, correspondingly, of the prod uction of a larger vortex.