Submitted as: development and technical paper
06 Sep 2022
Submitted as: development and technical paper | 06 Sep 2022
Status: a revised version of this preprint is currently under review for the journal GMD.

Improving the representation of shallow cumulus convection with the Simplified Higher-Order Closure Mass-Flux (SHOC+MF v1.0) approach

Maria J. Chinita1,2, Mikael Witte1,2,3, Marcin J. Kurowski1, Joao Teixeira1,2, Kay Suselj1,6, Georgios Matheou4, and Peter Bogenschutz5 Maria J. Chinita et al.
  • 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
  • 2Joint Institute for Regional Earth System Science and Engineering, University of California Los Angeles, Los Angeles, California, USA
  • 3Naval Postgraduate School, Monterey, California, USA
  • 4University of Connecticut, Storrs, Connecticut, USA
  • 5Lawrence Livermore National Laboratory, Livermore, California, USA
  • 6Running Tide Technologies, Inc, USA

Abstract. Parameterized boundary layer turbulence and moist convection remain some of the largest sources of uncertainty in general circulation models. High-resolution climate modeling aims to reduce that uncertainty by explicitly attempting to resolve deep moist convective motions. An example of such a model is the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM) with a target global resolution of 3.25 km, allowing for a more accurate representation of complex mesoscale deep convective dynamics. Yet, small-scale planetary boundary layer turbulence and shallow convection still need to be parameterized, which in SCREAM is accomplished through the TKE-based Simplified Higher-Order Closure (SHOC)—a simplified version of the assumed doubled-Gaussian PDF higher-order closure method. In this paper, we implement a stochastic multiplume Mass-Flux (MF) parameterization of dry and shallow convection in SCREAM to go beyond the limitations of double-Gaussian PDF closures and couple it to SHOC (SHOC+MF). The new parameterization implemented in a single-column model type version of SCREAM produces results for two shallow cumulus convection cases (marine and continental shallow convection) that agree well with the reference large-eddy simulation data, thus improving the general representation of the thermodynamic quantities and their turbulent fluxes as well as cloud macrophysics in the model. Furthermore, SHOC+MF parameterization shows weak sensitivity to the vertical grid resolution and model time step.

Maria J. Chinita et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2022-162', Anonymous Referee #1, 06 Oct 2022
  • RC2: 'Comment on gmd-2022-162', Anonymous Referee #2, 25 Oct 2022
  • RC3: 'Comment on gmd-2022-162', Anonymous Referee #3, 01 Nov 2022

Maria J. Chinita et al.

Maria J. Chinita et al.


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Short summary
Low clouds are one of the largest sources of uncertainty in climate prediction. In this paper, we introduce the first version of the unified turbulence and shallow convection parameterization named SHOC+MF developed to improve the representation of shallow cumulus clouds in the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM). Here, we also show promising preliminary results in a single-column model framework for two benchmark cases of shallow cumulus convection.