Hidden drifts in turbulence

The paper defines and discusses the concept of hidden drifts in two-dimensional turbulence. These are ordered components of the trajectories that average to zero and do not produce direct transport. Their effects appear in the evolution of the turbulence as a special type of fluxes, which consist of average motion of positive and negative fluctuations in opposite directions. We show that these fluxes have important nonlinear effects in confined plasmas and turbulent fluids. They provide a mechanism for zonal flow generation in the first case, while in the second case they determine the separation of the vorticity fluctuations according to their sign.