Publication Abstracts

Alexandrov et al. 2010

Alexandrov, M.D., A.S. Ackerman, and A. Marshak, 2010: Cellular statistical models of broken cloud fields. Part II: Comparison with dynamical model, statistics of diverse ensembles. J. Atmos. Sci., 67, 2152-2170, doi:10.1175/2010JAS3365.1.

Cellular statistical models are designed to provide a simple two-parameter characterization of the structure of broken cloud fields described through distributions of cloud fraction and of chord lengths for clouds and clear gaps. In these analytical models cloud fields are assumed to be formed on a semi-regular grid of cells (which can be vaguely interpreted as atmospheric convective cells). In a simple, discrete cell model, cell size is fixed and each cell can either be completely filled with cloud with some probability or remain empty. Extending the discrete model to a continuous case provides more realism by allowing arbitrary cloud and gap sizes. Here we test the continuous cellular model by comparing its statistics with those from large-eddy simulations (LES) of marine boundary-layer clouds based on case studies from three trade-cumulus field projects. The statistics largely agree, although the cellular model does not reproduce the probability of chord lengths peaking at sizes greater than the horizontal grid spacing found in the LES results. Exponential chord-length distributions follow from the assumption that the probability of any cell being cloudy is constant, appropriate for a given meteorological state (narrow sampling). Relaxing that assumption, and instead allowing this probability to have its own distribution, leads to a power-law distribution of chord lengths, appropriate to a broader sample of meteorological states (diverse sampling).

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BibTeX Citation

@article{al02400t,
  author={Alexandrov, M. D. and Ackerman, A. S. and Marshak, A.},
  title={Cellular statistical models of broken cloud fields. Part II: Comparison with dynamical model, statistics of diverse ensembles},
  year={2010},
  journal={J. Atmos. Sci.},
  volume={67},
  pages={2152--2170},
  doi={10.1175/2010JAS3365.1},
}

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RIS Citation

TY  - JOUR
ID  - al02400t
AU  - Alexandrov, M. D.
AU  - Ackerman, A. S.
AU  - Marshak, A.
PY  - 2010
TI  - Cellular statistical models of broken cloud fields. Part II: Comparison with dynamical model, statistics of diverse ensembles
JA  - J. Atmos. Sci.
VL  - 67
SP  - 2152
EP  - 2170
DO  - 10.1175/2010JAS3365.1
ER  -

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