Hetonic Explosions: The Breakup and Spread of Warm Pools as Explained by Baroclinic Point Vortices

Abstract

As an alternative to small amplitude continuous theories we study the disintegration of warm pools of fluid on a rotating earth using clouds of baroclinic point vortices, or hetons. The equations describing the motion of the hetons are relatively simple ordinary differential equations whose numerical integration makes it possible to physically interpret the temporal evolution of finite amplitude disturbances. Using experience with small numbers of hetons as a guide, a heuristic model is proposed. This predicts that the number of baroclinic vortices forming at the rim of a circular warm pool is given by the radius of the pool divided by 1.27 times the Rossby radius, while these vortices should expand outward at a rate given by 1.65 times the Rossby radius times the vorticity density of the pool. The first prediction is in agreement with previous laboratory experiments while the second has not previously been reported.