Dispersion of a vortex trajectory in 2D turbulence

The motion of coherent vortices in decaying 2D Navier-Stokes turbulence is studied using a probabilistic method. The vortex trajectory is predicted to be associated with a power-law dispersion [x(2)] proportional to t(eta), eta = 1.6. This theoretical result is discussed in relation to a numerical study of particle dispersion in strongly elliptic regions of equilibrium turbulence, which shows a law of eta approximate to 5/3. The prediction is in agreement with limited observations of drifting buoys in atmosphere and ocean.