Turbulent diffusion as a stochastic lagrangian process

The present status of stochastic Lagrangian models of turbulent diffusion is reviewed, beginning with a brief historical introduction. The mathematical and physical foundations of these models are described. The derivation of the model for the Lagrangian trajectory of a single particle is illustrated for one‐dimensional inhomogeneous Gaussian turbulence. Single‐particle models for non‐Gaussian turbulence in the convective boundary layer are described. The mean concentration in fixed co‐ordinates is calculated from the statistics of thousands of single‐particle trajectories. Another class of stochastic Lagrangian models gives the relative dispersion of particle pairs and the concentration variance. A list of references is provided for further study.