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Unified Entrainment and Detrainment Closures for Extended Eddy-Diffusivity Mass-Flux Schemes

Cohen, Yair and Lopez‐Gomez, Ignacio and Jaruga, Anna and He, Jia and Kaul, Colleen M. and Schneider, Tapio (2020) Unified Entrainment and Detrainment Closures for Extended Eddy-Diffusivity Mass-Flux Schemes. Journal of Advances in Modeling Earth Systems, 12 (9). Art. No. e2020MS002162. ISSN 1942-2466.

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We demonstrate that an extended eddy‐diffusivity mass‐flux (EDMF) scheme can be used as a unified parameterization of subgrid‐scale turbulence and convection across a range of dynamical regimes, from dry convective boundary layers, through shallow convection, to deep convection. Central to achieving this unified representation of subgrid‐scale motions are entrainment and detrainment closures. We model entrainment and detrainment rates as a combination of turbulent and dynamical processes. Turbulent entrainment/detrainment is represented as downgradient diffusion between plumes and their environment. Dynamical entrainment/detrainment is proportional to a ratio of a relative buoyancy of a plume and a vertical velocity scale, that is modulated by heuristic nondimensional functions which represent their relative magnitudes and the enhanced detrainment due to evaporation from clouds in drier environment. We first evaluate the closures off‐line against entrainment and detrainment rates diagnosed from large eddy simulations (LESs) in which tracers are used to identify plumes, their turbulent environment, and mass and tracer exchanges between them. The LES are of canonical test cases of a dry convective boundary layer, shallow convection, and deep convection, thus spanning a broad rangeof regimes. We then compare the LES with the full EDMF scheme, including the new closures, in a single‐column model (SCM). The results show good agreement between the SCM and LES in quantities that are key for climate models, including thermodynamic profiles, cloud liquid water profiles, and profiles of higher moments of turbulent statistics. The SCM also captures well the diurnal cycle of convection and the onset of precipitation.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemData/Code Paper
Cohen, Yair0000-0002-9615-2476
Lopez‐Gomez, Ignacio0000-0002-7255-5895
Jaruga, Anna0000-0003-3194-6440
Kaul, Colleen M.0000-0002-4462-0987
Schneider, Tapio0000-0001-5687-2287
Additional Information:© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 14 September 2020; Version of Record online: 14 September 2020; Accepted manuscript online: 04 August 2020; Manuscript accepted: 29 July 2020; Manuscript revised: 09 July 2020; Manuscript received: 01 May 2020. This research was made possible by the generosity of Eric and Wendy Schmidt by recommendation of the Schmidt Futures program, by Earthrise Alliance, Mountain Philanthropies, the Paul G. Allen Family Foundation, and the National Science Foundation (NSF, Award AGS‐1835860). I. L. would like to thank the Resnick Sustainability Institute at Caltech for fellowship support. Parts of the research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004) and funded through the internal Research and Technology Development program. The comments provided by Nadir Jeevanjee and one more anonymous reviewer greatly improved the final form of this work. © 2020. California Institute of Technology. Government sponsorship acknowledged. Data Availability Statements: The PyCLES code used to generate LES results is available at this site ( The SCM code is available at this site (
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Eric and Wendy SchmidtUNSPECIFIED
Schmidt Futures ProgramUNSPECIFIED
Earthrise AllianceUNSPECIFIED
Mountain PhilanthropiesUNSPECIFIED
Paul G. Allen Family FoundationUNSPECIFIED
Resnick Sustainability InstituteUNSPECIFIED
JPL Internal Research and Technology Development ProgramUNSPECIFIED
Subject Keywords:Unified parameterization; Convective parameterization; Eddy‐Diffusivity Mass‐Flux parameterization; Entrainment and Detrainment; Deep convection; Climate modeling
Issue or Number:9
Record Number:CaltechAUTHORS:20200820-123726127
Persistent URL:
Official Citation:Cohen, Y., Lopez‐Gomez, I., Jaruga, A., He, J., Kaul, C. M., & Schneider, T. (2020). Unified entrainment and detrainment closures for extended eddy‐diffusivity mass‐flux schemes. Journal of Advances in Modeling Earth Systems, 12, e2020MS002162.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105044
Deposited By: Tony Diaz
Deposited On:20 Aug 2020 19:58
Last Modified:03 Mar 2021 20:37

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