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Description of the NCAR
Contents
Description of the NCAR Community Atmosphere Model (CAM 3.0)
Contents
List of Figures
List of Tables
Acknowledgments
1. Introduction
1.1 Brief History
1.1.1 CCM0 and CCM1
1.1.2 CCM2
1.1.3 CCM3
1.2 Overview of CAM 3.0
2. Coupling of Dynamical Core and Parameterization Suite
3. Dynamics
3.1 Eulerian Dynamical Core
3.1.1 Generalized terrain-following vertical coordinates
3.1.2 Conversion to final form
3.1.3 Continuous equations using
3.1.4 Semi-implicit formulation
3.1.5 Energy conservation
3.1.6 Horizontal diffusion
3.1.7 Finite difference equations
3.1.8 Time filter
3.1.9 Spectral transform
3.1.10 Spectral algorithm overview
3.1.11 Combination of terms
3.1.12 Transformation to spectral space
3.1.13 Solution of semi-implicit equations
3.1.14 Horizontal diffusion
3.1.15 Initial divergence damping
3.1.16 Transformation from spectral to physical space
3.1.17 Horizontal diffusion correction
3.1.18 Semi-Lagrangian Tracer Transport
3.1.19 Mass fixers
3.1.20 Energy Fixer
3.1.21 Statistics Calculations
3.1.22 Reduced grid
3.2 Semi-Lagrangian Dynamical Core
3.2.1 Introduction
3.2.2 Vertical coordinate and hydrostatic equation
3.2.3 Semi-implicit reference state
3.2.4 Perturbation surface pressure prognostic variable
3.2.5 Extrapolated variables
3.2.6 Interpolants
3.2.7 Continuity Equation
3.2.8 Thermodynamic Equation
3.2.9 Momentum equations
3.2.10 Development of semi-implicit system equations
3.2.11 Trajectory Calculation
3.2.12 Mass and energy fixers and statistics calculations
3.3 Finite Volume Dynamical Core
3.3.1 Overview
3.3.2 The governing equations for the hydrostatic atmosphere
3.3.3 Horizontal discretization of the transport process on the sphere
3.3.4 A
vertically Lagrangian
and
horizontally Eulerian
control-volume discretization of the hydrodynamics
3.3.5 A mass, momentum, and total energy conserving mapping algorithm
3.3.6 Adjustment of specific humidity to conserve water
3.3.7 Further discussion
4. Model Physics
4.1 Deep Convection
4.1.1 Updraft Ensemble
4.1.2 Downdraft Ensemble
4.1.3 Closure
4.1.4 Numerical Approximations
4.1.5 Deep Convective Tracer Transport
4.2 Shallow/Middle Tropospheric Moist Convection
4.3 Evaporation of convective precipitation
4.4 Conversion to and from dry and wet mixing ratios for trace constituents in the model
4.5 Prognostic Condensate and Precipitation Parameterization
4.5.1 Introductory comments
4.5.2 Description of the macroscale component
4.5.3 Description of the microscale component
4.6 Dry Adiabatic Adjustment
4.7 Parameterization of Cloud Fraction
4.8 Parameterization of Shortwave Radiation
4.8.1 Diurnal cycle
4.8.2 Formulation of shortwave solution
4.8.3 Aerosol properties and optics
4.8.3.1 Introduction
4.8.3.2 Description of aerosol climatologies and data sets
4.8.3.3 Calculation of aerosol optical properties
4.8.3.4 Calculation of aerosol shortwave effects and radiative forcing
4.8.3.5 Globally uniform background sulfate aerosol
4.8.4 Cloud Optical Properties
4.8.4.1 Parameterization of effective radius
4.8.4.2 Dependencies involving effective radius
4.8.5 Cloud vertical overlap
4.8.5.1 Conversion of cloud amounts to binary cloud profiles
4.8.5.2 Maximum-random overlap assumption
4.8.5.3 Low, medium and high cloud overlap assumptions (diagnostics)
4.8.5.4 Computation of fluxes and heating rates with overlap
4.8.6
-Eddington solution for a single layer
4.8.7 Combination of layers
4.8.8 Acceleration of the adding method in all-sky calculations
4.8.9 Methods for reducing the number of binary cloud configurations
4.8.10 Computation of shortwave fluxes and heating rates
4.9 Parameterization of Longwave Radiation
4.9.1 Major absorbers
4.9.2 Water vapor
4.9.3 Trace gas parameterizations
4.9.4 Mixing ratio of trace gases
4.9.5 Cloud emissivity
4.9.6 Numerical algorithms and cloud overlap
4.10 Surface Exchange Formulations
4.10.1 Land
4.10.1.1 Roughness lengths and zero-plane displacement
4.10.1.2 Monin-Obukhov similarity theory
4.10.2 Ocean
4.10.3 Sea Ice
4.11 Vertical Diffusion and Boundary Layer Processes
4.11.1 Free atmosphere turbulent diffusivities
4.11.2 ``Non-local'' atmospheric boundary layer scheme
4.11.3 Discretization of the vertical diffusion equations
4.11.4 Solution of the vertical diffusion equations
4.11.5 Discrete equations for
,
, and
4.12 Sulfur Chemistry
4.12.1 Emissions
4.12.2 Chemical Reactions
4.12.2.1 Gas-Phase Reactions
4.12.2.2 Aqueous-Phase Reactions
4.12.3 Wet Deposition
4.12.4 Dry Deposition
4.13 Prognostic Greenhouse Gases
5. Slab Ocean Model
5.1 Open Ocean Component
5.2 Thermodynamic Sea Ice Model
5.3 Evaluation of the Ocean
Flux
6. Sea Ice Thermodynamics
6.1 Basic assumptions
6.2 Fundamental Equations
6.3 Snow and Ice Albedo
6.4 Ice to Atmosphere Flux Exchange
6.5 Ice to Ocean Flux Exchange
6.6 Brine Pockets and Internal Energy of Sea Ice
6.7 Open-Water Growth and Ice Concentration Evolution
6.8 Snow-Ice Conversion
6.9 Numerics
6.9.1 Case I: Snow accumulated with no melting
6.9.2 Case II: Snow free with no melting
6.9.3 Case III: Snow accumulated with melting
6.9.4 Case IV: No snow with melting
6.9.5 Temperature Adjustment Due to Melt/Growth
7. Initial and Boundary Data
7.1 Initial Data
7.2 Boundary Data
A. Physical Constants
B. Acronyms
C. Resolution and dycore-dependent parameters
Bibliography
About this document ...
Jim McCaa 2004-06-22
-Eddington solution for a single layer
, 
, and 
Flux