TY  - JOUR
A1  - Bašták Ďurán, Ivan
A1  - Sakradzija, Mirjana
A1  - Schmidli, Jürg
T1  - The two-energies turbulence scheme coupled to the assumed PDF method
T2  - Journal of advances in modeling earth systems
N2  - An update of the two-energy turbulence scheme is presented, the 2TE + APDF scheme. The original version of the two-energy scheme is able to successfully model shallow convection without the need of an additional parameterization for non-local fluxes. However, the performance of the two-energy scheme is worse in stratocumulus cases, where it tends to overestimate the erosion of the stable layers. We have identified the causes: the non-local stability parameter does not consider local stratification, the scheme lacks an internal parameter that could distinguish between a shallow convection regime and a stratocumulus regime, and it uses an inflexible turbulence length scale formulation. To alleviate this problem, we propose several modifications: an update of the stability parameter, a modified computation of the turbulence length scale, and the introduction of the entropy potential temperature to distinguish between a shallow convection and a stratocumulus regime. In addition, the two-energy scheme is coupled to a simplified assumed probability density function method in order to achieve a more universal representation of the cloudy regimes. The updated turbulence scheme is evaluated for several idealized cases and one selected real case in the ICOsahedral Nonhydrostatic (ICON) modeling framework. The results show that the updated scheme corrects the overmixing problem in the stratocumulus cases. The performance of the updated scheme is comparable to the operational setup, and can be thus used instead of the operational turbulence and shallow convection scheme in ICON. Additionally, the updated scheme improves the coupling with dynamics, which is beneficial for the modeling of coherent flow structures in the atmospheric boundary layer.
KW  - turbulence
KW  - unified parameterization
KW  - large eddy simulation
KW  - atmospheric boundary layer
KW  - shallow convection
KW  - assumed PDF method
Y1  - 2022
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/79349
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-793497
SN  - 1942-2466
N1  - This research was funded by the Hans Ertel Centre for Weather Research of DWD (third phase, The Atmospheric Boundary Layer in Numerical Weather Prediction) Grant No. 4818DWDP4; and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—TRR 301—Project-ID 428312742. This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID bb1096. Open access funding enabled and organized by Projekt DEAL.
N1  - The data for this study were generated with the large eddy simulation model MicroHH, which are openly available in Zenodo at https://zenodo.org/record/822842 (C. C. van Heerwaarden et al., 2017). The configuration files, outputs, and visualization scripts for the ICOsahedral Nonhydrostatic (ICON) simulations are openly available in Zenodo at: https://doi.org/10.5281/zenodo.6403030 [Titel anhand dieser DOI in Citavi-Projekt übernehmen] (Bašták Ďurán et al., 2022). The code of the 2TE + APDF scheme in ICON, together with the configuration for the idealized cases and the python scripts for the generation of the forcing can be accessed after registration at the internal DWD GitLab repository (https://gitlab.dkrz.de/) in the icon-nwp/icon-nwp-scm-2te + apdf branch. All figures were generated with the Python matplotlib package (Hunter, 2007). This project took advantage of netCDF software developed by UCAR/Unidata (http://doi.org/10.5065/D6H70CW6).
VL  - 14
IS  - 5, art. e2021MS002922
SP  - 1
EP  - 19
PB  - [Verlag nicht ermittelbar]
CY  - Fort Collins, Colo.
ER  -