Publication Abstracts

Lin et al. 2015

Lin, W., Y. Liu, A.M. Vogelmann, A.M. Fridlind, S. Endo, S. Feng, T. Toto, Z. Li, and M. Zhang, 2015: RACORO continental boundary layer cloud investigations. Part III: Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus. J. Geophys. Res. Atmos., 120, no. 12, 6015-6033, doi:10.1002/2014JD022524.

Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) Project has constructed case studies from the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.

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BibTeX Citation

@article{li02700u,
  author={Lin, W. and Liu, Y. and Vogelmann, A. M. and Fridlind, A. M. and Endo, S. and Feng, S. and Toto, T. and Li, Z. and Zhang, M.},
  title={RACORO continental boundary layer cloud investigations. Part III: Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus},
  year={2015},
  journal={J. Geophys. Res. Atmos.},
  volume={120},
  number={12},
  pages={6015--6033},
  doi={10.1002/2014JD022524},
}

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RIS Citation

TY  - JOUR
ID  - li02700u
AU  - Lin, W.
AU  - Liu, Y.
AU  - Vogelmann, A. M.
AU  - Fridlind, A. M.
AU  - Endo, S.
AU  - Feng, S.
AU  - Toto, T.
AU  - Li, Z.
AU  - Zhang, M.
PY  - 2015
TI  - RACORO continental boundary layer cloud investigations. Part III: Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus
JA  - J. Geophys. Res. Atmos.
VL  - 120
IS  - 12
SP  - 6015
EP  - 6033
DO  - 10.1002/2014JD022524
ER  -

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