A numerical investigation of boundary layer quasi-equilibrium

Despite the large energy input from surface evaporation, the moist static energy (MSE) of the tropical boundary layer remains relatively constant on large spatial and temporal scales due to lifting of vapor by cloudy updrafts and the addition of dry air from the layers above. Arakawa and Schubert (1...

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Bibliographic Details
Published in:Geophysical research letters 2015-01, Vol.42 (2), p.550-556
Main Authors: Thayer-Calder, K., Randall, David
Format: Article
Language:English
Subjects:
Aerodynamics
Air entrainment
Balances (scales)
Boundary layer
Boundary layers
Computational fluid dynamics
Computer simulation
convection
Downdraft
Dry air
Drying
Entrainment
Evaporation
Mathematical models
Moist static energy
Numerical simulations
Parametrization
tropical
Tropical climate
Turbulence
Turbulent boundary layer
Turbulent entrainment
Updraft
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Summary:Despite the large energy input from surface evaporation, the moist static energy (MSE) of the tropical boundary layer remains relatively constant on large spatial and temporal scales due to lifting of vapor by cloudy updrafts and the addition of dry air from the layers above. Arakawa and Schubert (1974) suggested that drying is due mainly to clear‐air turbulent entrainment between cloudy updrafts, while Raymond (1995) described drying due mainly to convective downdrafts. We used cloud‐resolving numerical simulations to investigate the transport of MSE into the boundary layer and found turbulent entrainment between clouds to be the dominant process. Key Points The tropical boundary layer is dried more by entrainment than by downdrafts Downdrafts sometimes inject high‐energy air into the boundary layer Models need better parameterizations of entrainment at the boundary layer top
ISSN:0094-8276
1944-8007
DOI:10.1002/2014GL062649