O'Brien cubic polynomial

{
  "id": "MLC-T-MET-010649",
  "term": "O'Brien cubic polynomial",
  "field": "Meteorology and atmospheric science",
  "definition": "A mathematical function used to represent the vertical profile of turbulent exchange coefficients, such as eddy diffusivity, within the atmospheric boundary layer. This third-order polynomial is constrained by known values of the coefficient and its vertical gradient at two different heights, usually the surface and the top of the boundary layer. The resulting profile smoothly connects the surface layer, where fluxes are well-defined, to the upper part of the mixed layer, providing a physically plausible representation for use in numerical models.",
  "see_also": [
    "K'' theory",
    "gradient transport theory",
    "first-order closure",
    "closure assumptions"
  ],
  "url": "https://mlchart.com/terminology/meteorology/o-brien-cubic-polynomial/"
}