Three-dimensional regions in a turbulent flow with characteristic structures and lifetimes in terms of velocity, temperature, etc. , that are significantly larger or longer-lived than the smallest local scales. Much of the turbulent transport, conversion of mean flow energy into turbulent eddies, nonlinear transfer into smaller scales, and eventual dissipation is associated with coherent structures. Examples include gust microfronts and horseshoe vortices in the surface layer, convective plumes, and longitudinal roll vortices. See longitudinal rolls, convective plume, Langmuir circulation.