Concepedia

Cospectral similarity in the atmospheric surface layer

Quarterly Journal of the Royal Meteorological Society · 1972 · 241 citations · 14 references

TL;DR

Surface‑layer turbulence structure is governed by four parameters, but in two asymptotic limits these reduce to three. The study introduces the term “local z‑less stratification” to describe the stable limit where the height coordinate z drops out. In this stable regime the governing equations no longer involve z, simplifying the turbulence description. They find that in the unstable limit—termed local free convection—the surface stress becomes negligible, and both limits yield explicit predictions for stress and heat flux cospectra that are largely confirmed by 1968 Kansas experiment data even near neutral conditions.

Abstract

Abstract There are two asymptotic cases where the four parameters which determine surface layer turbulence structure reduce to three. In the unstable limit, which we call local free convection, the surface stress is no longer important. In the stable limit z no longer enters; we propose the name ‘local z ‐less stratification’ for this state. In both cases explicit predictions result for various properties of the cospectra of stress and heat flux. Although the predictions are based on asymptotic arguments and therefore might be expected to hold only at large ∣ z / L ∣ values, data from the 1968 Kansas experiments show that most predictions are valid fairly close to neutral.