Eddy Diffusivity

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Joao Paulo Teixeira - One of the best experts on this subject based on the ideXlab platform.

Kay Suselj - One of the best experts on this subject based on the ideXlab platform.

Georgios Matheou - One of the best experts on this subject based on the ideXlab platform.

  • an integrated tke based Eddy Diffusivity mass flux boundary layer closure for the dry convective boundary layer
    Journal of the Atmospheric Sciences, 2011
    Co-Authors: Marcin L Witek, Joao Paulo Teixeira, Georgios Matheou
    Abstract:

    AbstractThis study presents a new approach to the Eddy Diffusivity/mass flux (EDMF) framework for the modeling of convective boundary layers. At the root of EDMF lies a decomposition of turbulent transport mechanisms into strong ascending updrafts and smaller-scale turbulent motions. The turbulent fluxes can be therefore described using two conventional approaches: mass flux (MF) for the organized thermals and Eddy Diffusivity (ED) for the remaining turbulent field. Since the intensities of both MF and ED transports depend on the kinetic energy of the turbulent motions, it seems reasonable to formulate an EDMF framework based on turbulent kinetic energy (TKE). Such an approach allows for more physical and less arbitrary formulations of parameters in the model. In this study the EDMF–TKE coupling is achieved through the use of (i) a new parameterization for the lateral entrainment coefficient e and (ii) the MF contribution to the buoyancy source of TKE. Some other important features of the EDMF parameteriz...

  • An Integrated TKE-Based Eddy Diffusivity/Mass Flux Boundary Layer Closure for the Dry Convective Boundary Layer
    Journal of the Atmospheric Sciences, 2011
    Co-Authors: Marcin L Witek, Joao Paulo Teixeira, Georgios Matheou
    Abstract:

    AbstractThis study presents a new approach to the Eddy Diffusivity/mass flux (EDMF) framework for the modeling of convective boundary layers. At the root of EDMF lies a decomposition of turbulent transport mechanisms into strong ascending updrafts and smaller-scale turbulent motions. The turbulent fluxes can be therefore described using two conventional approaches: mass flux (MF) for the organized thermals and Eddy Diffusivity (ED) for the remaining turbulent field. Since the intensities of both MF and ED transports depend on the kinetic energy of the turbulent motions, it seems reasonable to formulate an EDMF framework based on turbulent kinetic energy (TKE). Such an approach allows for more physical and less arbitrary formulations of parameters in the model. In this study the EDMF–TKE coupling is achieved through the use of (i) a new parameterization for the lateral entrainment coefficient e and (ii) the MF contribution to the buoyancy source of TKE. Some other important features of the EDMF parameteriz...

Daniel Chung - One of the best experts on this subject based on the ideXlab platform.

  • a unified model for moist convective boundary layers based on a stochastic Eddy Diffusivity mass flux parameterization
    Journal of the Atmospheric Sciences, 2013
    Co-Authors: Kay Suselj, Joao Paulo Teixeira, Daniel Chung
    Abstract:

    AbstractA single-column model (SCM) is developed for representing moist convective boundary layers. The key component of the SCM is the parameterization of subgrid-scale vertical mixing, which is based on a stochastic Eddy-Diffusivity/mass-flux (EDMF) approach. In the EDMF framework, turbulent fluxes are calculated as a sum of the turbulent kinetic energy–based Eddy-Diffusivity component and a mass-flux component. The mass flux is modeled as a fixed number of steady-state plumes. The main challenge of the mass-flux model is to properly represent cumulus clouds, which are modeled as moist plumes. The solutions have to account for a realistic representation of condensation within the plumes and of lateral entrainment into the plumes. At the level of mean condensation within the updraft, the joint pdf of moist conserved variables and vertical velocity is used to estimate the proportion of dry and moist plumes and is sampled in a Monte Carlo way creating a predefined number of plumes. The lateral entrainment ...

  • A Unified Model for Moist Convective Boundary Layers Based on a Stochastic Eddy-Diffusivity/Mass-Flux Parameterization
    Journal of the Atmospheric Sciences, 2013
    Co-Authors: Kay Suselj, Joao Paulo Teixeira, Daniel Chung
    Abstract:

    AbstractA single-column model (SCM) is developed for representing moist convective boundary layers. The key component of the SCM is the parameterization of subgrid-scale vertical mixing, which is based on a stochastic Eddy-Diffusivity/mass-flux (EDMF) approach. In the EDMF framework, turbulent fluxes are calculated as a sum of the turbulent kinetic energy–based Eddy-Diffusivity component and a mass-flux component. The mass flux is modeled as a fixed number of steady-state plumes. The main challenge of the mass-flux model is to properly represent cumulus clouds, which are modeled as moist plumes. The solutions have to account for a realistic representation of condensation within the plumes and of lateral entrainment into the plumes. At the level of mean condensation within the updraft, the joint pdf of moist conserved variables and vertical velocity is used to estimate the proportion of dry and moist plumes and is sampled in a Monte Carlo way creating a predefined number of plumes. The lateral entrainment ...

Marcin J Kurowski - One of the best experts on this subject based on the ideXlab platform.

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