ALBERT

Description: The representation of deep convective clouds by convection‐permitting models could be improved by better parameterising the subgrid turbulent fluxes. Following Verrelle et al. (2017), a large eddy simulation (LES) of a population of convective clouds at a 50‐m grid spacing was explored during the cloud life cycle to characterize the second‐order moment turbulent fluxes. The reference turbulence fields were deduced by coarse‐graining the LES outputs at horizontal grid resolutions of 500 m, 1 km and 2 km. The ability of three parameterizations, the traditional K‐gradient Cuxart et al. (2000) (CBR) and Smagorinsky (1963) formulations and the Moeng (2014) (MOENG) approach based on the horizontal gradients of the resolved variables, to reproduce the thermodynamical and dynamical fluxes was assessed in an offline configuration via a comparison to the reference fields. MOENG was the most appropriate scheme to represent the vertical and horizontal heat fluxes at all grid spacings in the clouds and their environment over the entire cloud life cycle including the appropriate representation of countergradient areas. It also represented the vertical and horizontal moisture fluxes at the 1km and 500‐m grid spacings the best, while its advantage is reduced at a grid spacing of 2 km as CBR performed slightly better for the statistical scores. MOENG was also able to represent the dynamical covariances well at grid spacings of 1 km and 500 m, even though the statistical scores were not as good as those obtained for the thermodynamical fluxes. The dynamical variances were well represented by CBR; however, for this offline evaluation, the subgrid TKE, present in CBR formulations, is directly computed from the LES outputs giving CBR an advantage over the two other diagnosed parameterizations. Also, the reference fluxes revealed an anisotropic deformation of the turbulence throughout the troposphere, which was only captured by MOENG. This article is protected by copyright. All rights reserved.