Publication Abstracts

Yao and Del Genio 1989

Yao, M.-S., and A.D. Del Genio, 1989: Effects of cumulus entrainment and multiple cloud types on a January global climate model simulation. J. Climate, 2, 850-863, doi:10.1175/1520-0442(1989)002<0850:EOCEAM>2.0.CO;2.

An improved version of the GISS Model II cumulus parameterization designed for long-term climate integrations is used to study the effects of entrainment and multiple cloud types on the January climate simulation. Instead of prescribing convective mass as a fixed fraction of the cloud base grid-box mass, it is calculated based on the closure assumption that the cumulus convection restores the atmosphere to a neutral moist convective state at cloud base. This change alone significantly improves the distribution of precipitation, convective mass exchanges and frequencies in the January climate. The vertical structure of the tropical atmosphere exhibits quasi-equilibrium behavior when this closure is used, even though there is no explicit constraint applied above cloud base. Global aspects of the simulation using the neutral buoyancy closure are almost identical to those of obtained in a previous study with a closure relating cumulus mass flux explicitly to large-scale forcing.

A prescription of 0.2 /km or the fractional rate of entrainment lowers the peak of the convective heating profile, reduces equatorial specific humidities in the upper atmosphere to more realistic values, and greatly increases eddy kinetic energy at the equator due to reduced momentum mixing. With two cloud types per convective event, each cloud type having a prescribed size and entrainment rate, a clear bimodal distribution of convective mass flux is obtained in strong convective events. At the same time, many of the desirable climate features produced by the neutral buoyancy and entrainment experiments are preserved.

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BibTeX Citation

@article{ya07000g,
  author={Yao, M.-S. and Del Genio, A. D.},
  title={Effects of cumulus entrainment and multiple cloud types on a January global climate model simulation},
  year={1989},
  journal={J. Climate},
  volume={2},
  pages={850--863},
  doi={10.1175/1520-0442(1989)002%3C0850%3AEOCEAM%3E2.0.CO;2},
}

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RIS Citation

TY  - JOUR
ID  - ya07000g
AU  - Yao, M.-S.
AU  - Del Genio, A. D.
PY  - 1989
TI  - Effects of cumulus entrainment and multiple cloud types on a January global climate model simulation
JA  - J. Climate
VL  - 2
SP  - 850
EP  - 863
DO  - 10.1175/1520-0442(1989)002%3C0850%3AEOCEAM%3E2.0.CO;2
ER  -

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