Center for Renewable Resource and Integration, Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
The role of nonlocal transport on the development and maintenance of marine stratocumulus (Sc) clouds in coarse-resolution models is investigated, with a special emphasis on the downdraft contribution. A new parameterization of cloud-top-triggered downdrafts is proposed and validated against large-eddy simulation (LES) for two Sc cases. The applied nonlocal mass-flux scheme is part of the stochastic multiplume eddy-diffusivity/mass-flux (EDMF) framework decomposing the turbulent transport into local and nonlocal contributions. The complementary local turbulent transport is represented with the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme. This EDMF version has been implemented in the Weather Research and Forecasting (WRF) single-column model (SCM) and tested for three model versions: without mass flux, with updrafts only, and with both updrafts and downdrafts. In the LES, the downdraft and updraft contributions to the total heat and moisture transport are comparable and significant. The WRF SCM results show a good agreement between the parameterized downdraft turbulent transport and LES. While including updrafts greatly improves the modeling of Sc clouds over the simulation without mass flux, the addition of downdrafts is less significant, although it helps improve the moisture profile in the planetary boundary layer.
Wu, Elynn, Yang, Handa, Kleissl, Jan, Suselj, Kay, Kurowski, Marcin J., & Teixeira, João (2020). On the Parameterization of Convective Downdrafts for Marine Stratocumulus Clouds. Monthly Weather Review, 148(5). https://doi.org/10.1175/MWR-D-19-0292.1
@article{osti_1632764,
author = {Wu, Elynn and Yang, Handa and Kleissl, Jan and Suselj, Kay and Kurowski, Marcin J. and Teixeira, João},
title = {On the Parameterization of Convective Downdrafts for Marine Stratocumulus Clouds},
annote = {The role of nonlocal transport on the development and maintenance of marine stratocumulus (Sc) clouds in coarse-resolution models is investigated, with a special emphasis on the downdraft contribution. A new parameterization of cloud-top-triggered downdrafts is proposed and validated against large-eddy simulation (LES) for two Sc cases. The applied nonlocal mass-flux scheme is part of the stochastic multiplume eddy-diffusivity/mass-flux (EDMF) framework decomposing the turbulent transport into local and nonlocal contributions. The complementary local turbulent transport is represented with the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme. This EDMF version has been implemented in the Weather Research and Forecasting (WRF) single-column model (SCM) and tested for three model versions: without mass flux, with updrafts only, and with both updrafts and downdrafts. In the LES, the downdraft and updraft contributions to the total heat and moisture transport are comparable and significant. The WRF SCM results show a good agreement between the parameterized downdraft turbulent transport and LES. While including updrafts greatly improves the modeling of Sc clouds over the simulation without mass flux, the addition of downdrafts is less significant, although it helps improve the moisture profile in the planetary boundary layer.},
doi = {10.1175/MWR-D-19-0292.1},
url = {https://www.osti.gov/biblio/1632764},
journal = {Monthly Weather Review},
issn = {ISSN 0027-0644},
number = {5},
volume = {148},
place = {United States},
publisher = {American Meteorological Society},
year = {2020},
month = {05}}