Finite-core hetons: stability and interactions

The dynamics of vertically compensated two-layer vortices (hetons) with fin ite cores are examined within the context of the quasi-geostrophic approxim ation on the f-plane. The two-layer version of the contour dynamics method is used, and complemented by the so-called contour surgery technique. Speci al attention is paid to two-heton interactions when the initial locations o f the vortex patches are symmetrical. A classification of the different reg imes observed is made according to external parameters, namely geometrical parameters and stratification. In this parameter space, novel quasi-station ary states resulting from collisions between two hetons may be observed: (i ) formation of a configuration consisting of two-layer vortices moving in o pposite directions and, as a special case, a configuration analogous to the 'klapstoss' billiard shot, (ii) absorption of one heton by the other and s ubsequent movement of a new dipole, (iii) formation of two-layer dipoles, l arger than the original hetons, associated with rotating peripheral satelli te eddies in their wakes. Some of these results may have implications for t he analysis of mesoscale vortices in the ocean.