A cumulus parameterization including mass fluxes, vertical momentum dynamics, and mesoscale effects

Journal Article · Mon Mar 15 04:00:00 EST 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<0889:ACPIMF>2.0.CO;2· OSTI ID:6534738

Donner, L J ^[1]

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1. Princeton Univ., NJ (United States)

A formulation for parameterizing cumulus convection, which treats cumulus vertical momentum dynamics and mass fluxes consistently, is presented. This approach predicts the penetrative extent of cumulus updrafts on the basis of their vertical momentum and provides a basis for treating cumulus microphysics using formulations that depend on vertical velocity. Treatments for cumulus microphysics are essential if the water budgets of convective systems are to be evaluated for treating mesoscale stratiform processes associated with convection, which are important for radiative interactions influencing climate. The water budget of the cumulus updrafts is used to drive a semi-empirical parameterization for the large-scale effects of the mesoscale circulations associated with deep convection. The parameterization was applied to two tropical thermodynamic profiles whose diagnosed forcing by convective systems differed significantly. The deepest of the updrafts penetrated the upper troposphere, while the shallower updrafts penetrated into the region of the mesoscale anvil. The relative numbers of cumulus updrafts of characteristic vertical velocities comprising the parameterized ensemble corresponded well with available observations. The large-scale heating produced by the ensemble without mesoscale circulations was concentrated at lower heights than observed or was characterized by excessive peak magnitudes. An unobserved large-scale source of water vapor was produced in the middle troposphere. When the parameterization for mesoscale effects was added, the large-scale thermal and moisture forcing predicted by the parameterization agreed well with observations for both cases. The significance of mesoscale processes suggests that future cumulus parameterization development will need to treat some radiative processes.

• OSTI ID: 6534738
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 50:6; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ANGULAR MOMENTUM
ATMOSPHERIC CIRCULATION
CLOUDS
CONVECTION
DYNAMICS
EARTH ATMOSPHERE
ENERGY TRANSFER
FLUIDS
GASES
HEAT TRANSFER
LINEAR MOMENTUM
MASS TRANSFER
MATHEMATICAL MODELS
MECHANICS
PARTICLE MODELS
SCALE MODELS
STATISTICAL MODELS
STRUCTURAL MODELS
THERMODYNAMIC MODEL
TROPOSPHERE
VAPORS
VELOCITY
WATER VAPOR