scholarly journals Effects of Diurnal Variations on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study

2007 ◽  
Vol 64 (2) ◽  
pp. 656-664 ◽  
Author(s):  
Shouting Gao ◽  
Yushu Zhou ◽  
Xiaofan Li
Keyword(s):  
Equilibrium State ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Diurnal Variations ◽  
Equilibrium States ◽  
Sea Surface ◽  
Two Dimensional ◽  
Time Invariant

Abstract Effects of diurnal variations on tropical heat and water vapor equilibrium states are investigated based on hourly data from two-dimensional cloud-resolving simulations. The model is integrated for 40 days and the simulations reach equilibrium states in all experiments. The simulation with a time-invariant solar zenith angle produces a colder and drier equilibrium state than does the simulation with a diurnally varied solar zenith angle. The simulation with a diurnally varied sea surface temperature generates a colder equilibrium state than does the simulation with a time-invariant sea surface temperature. Mass-weighted mean temperature and precipitable water budgets are analyzed to explain the thermodynamic differences. The simulation with the time-invariant solar zenith angle produces less solar heating, more condensation, and consumes more moisture than the simulation with the diurnally varied solar zenith angle. The simulation with the diurnally varied sea surface temperature produces a colder temperature through less latent heating and more IR cooling than the simulation with the time-invariant sea surface temperature.

scholarly journals Microphysical and Radiative Effects of Ice Clouds on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study

2007 ◽  
Vol 135 (7) ◽  
pp. 2794-2802 ◽  
Author(s):  
Fan Ping ◽  
Zhexian Luo ◽  
Xiaofan Li
Keyword(s):  
Equilibrium State ◽  
Vapor Condensation ◽  
Equilibrium States ◽  
Two Dimensional ◽  
Radiative Effects ◽  
Ice Clouds ◽  
Surface Rain Rate ◽  
Ice Microphysics ◽  
Time Invariant ◽  
Rain Rates

Abstract The microphysical and radiative effects of ice clouds on tropical equilibrium states are investigated based on three two-dimensional cloud-resolving simulations imposed by zero vertical velocity and time-invariant zonal wind and sea surface temperature. An experiment without ice microphysics (ice microphysical and radiative effects; C00), another experiment without ice radiative effects (CI0), and the control experiment (CIR) are carried out. The model with cyclic lateral boundaries is integrated for 40 days to reach equilibrium states in all experiments. CI0 produces a colder and drier equilibrium state than CIR and C00 do through generating a larger IR cooling, a larger vapor condensation rate, and consuming a larger amount of water vapor. A larger surface rain rate occurs in CI0 than in CIR and C00. The ice radiative effects on thermodynamic equilibrium states are stronger than the ice microphysical effects so that the exclusion of ice microphysics yields a colder and drier equilibrium state in C00 than in CIR. The ice radiative effects and the ice microphysical effects on surface rainfall processes are largely offset, which leads to similar zonal-mean surface rain rates in C00 and CIR.

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