Eddy Diffusivity/Mass Flux and Shallow Cumulus Boundary Layer: An Updraft PDF Multiple Mass Flux Scheme
- 1 May 2012
- journal article
- Published by American Meteorological Society in Journal of the Atmospheric Sciences
- Vol. 69 (5), 1513-1533
- https://doi.org/10.1175/jas-d-11-090.1
Abstract
In this study, the eddy diffusivity/mass flux (EDMF) approach is used to combine parameterizations of nonprecipitating moist convection and boundary layer turbulence. The novel aspect of this EDMF version is the use of a probability density function (PDF) to describe the moist updraft characteristics. A single bulk dry updraft is initialized at the surface and integrated vertically. At each model level, the possibility of condensation within the updraft is considered based on the PDF of updraft moist conserved variables. If the updraft partially condenses, it is split into moist and dry updrafts, which are henceforth integrated separately. The procedure is repeated at each of the model levels above. The single bulk updraft ends up branching into numerous moist and dry updrafts. With this new approach, the need to define a cloud-base closure is circumvented. This new version of EDMF is implemented in a single-column model (SCM) and evaluated using large-eddy simulation (LES) results for the Barbados Oceanographic and Meteorological Experiment (BOMEX) representing steady-state convection over ocean and the Atmospheric Radiation Measurement (ARM) case representing time-varying convection over land. The new EDMF scheme is able to represent the properties of shallow cumulus and turbulent fluxes in cumulus-topped boundary layers realistically. The parameterized updraft properties partly account for the behavior of the tail of the PDF of moist conserved variables. It is shown that the scheme is not particularly sensitive to the vertical resolution of the SCM or the main model parameters.Keywords
This publication has 37 references indexed in Scilit:
- Performance of an Eddy Diffusivity–Mass Flux Scheme for Shallow Cumulus Boundary LayersMonthly Weather Review, 2010
- A Simple Parameterization Coupling the Convective Daytime Boundary Layer and Fair-Weather CumuliJournal of the Atmospheric Sciences, 2005
- The Cumulus Parameterization Problem: Past, Present, and FutureJournal of Climate, 2004
- A Multiple Mass Flux Parameterization for the Surface-Generated Convection. Part II: Cloudy CoresJournal of the Atmospheric Sciences, 2004
- Parameterization of Joint Frequency Distributions of Potential Temperature and Water Vapor Mixing Ratio in the Daytime Convective Boundary LayerJournal of the Atmospheric Sciences, 2004
- A simple formulation for the eddy‐diffusivity parameterization of cloud‐topped boundary layersGeophysical Research Letters, 2003
- A Multiple Mass-Flux Parameterization for the Surface-Generated Convection. Part I: Dry PlumesJournal of the Atmospheric Sciences, 2003
- Large‐eddy simulation of the diurnal cycle of shallow cumulus convection over landQuarterly Journal of the Royal Meteorological Society, 2002
- Modeling of Trade Wind Cumuli with a Low-Order Turbulence Model: Toward a Unified Description of Cu and Se Clouds in Meteorological ModelsJournal of the Atmospheric Sciences, 1995
- Model of the Thermodynamic Structure of the Trade-Wind Boundary Layer: Part I. Theoretical Formulation and Sensitivity TestsJournal of the Atmospheric Sciences, 1979