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Coupled Climate Models. OCEAN-ATMOSPHERE INTERACTIONS. What is climate?. Different meanings an external, forcing agent influence on society and socio-economics a background norm on which weather is imposed temperature, rain, and humidity. Climatic System. 5 Major Components Hydrosphere
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Coupled Climate Models OCEAN-ATMOSPHERE INTERACTIONS
What is climate? • Different meanings • an external, forcing agent • influence on society and socio-economics • a background norm on which weather is imposed • temperature, rain, and humidity
Climatic System 5 Major Components • Hydrosphere • Atmosphere • Cryosphere • Lithosphere • Biosphere
Why does climate vary? VARIATIONS IN CLIMATE COMPONENTS
Climate Forcings: the basis for change • Forcing: a change on the planetary energy balance system (flux) • 2 separate categories: • External Forcings • Internal Forcings • Human • Natural
Climate Forcings: External • Milankovitch Cycles • Eccentricity • Obliquity • Precession • Solar Activity • Comet/meteorite impacts
Greenhouse Gases Tropospheric Aerosols Ozone Depletion Land Surface Changes KNOWN FORCINGS Climate Forcings: InternalHuman induced
Climate Forcings: InternalNatural • Ocean circulation changes • Volcanic eruptions • Heat Transfer from interior
Measurements that Drive the Models • Sea surface temperature • Air temperature and humidity • Wind velocity • Net radiation flux at ocean and underlying surfaces and upper atmospheric boundary • Fluxes of momentum, heat and moisture at the ocean-atmosphere boundary
Combine oceanic and atmospheric models Coupled Climate Model
General Circulation Model: GCM • 3-dimensional model • scaling issues
General Circulation Model: GCM • Solve for the main features of the atmosphere and ocean through a series of equations
AGCM variables • Surface Pressure • 2 horizontal wind components • Temperature • Moisture • Geopotential height
AGCM: Physical Processes • Radiative Transfer • daily and annular cycles • short- and long-wave • clouds • Boundary Layer • friction • diurnal temperature and humidity variations
AGCM: Physical Processes • Large-scale rainfall • Convection
AGCM: Physical Processes • Land Surface Parameterization • gravity wave drag
Oceanic GCM • Drivers • Winds • Salinity and density • Detailed schemes • Stronger currents on western sides of basin
OGCMs • Swamp Model • Slab Model • Detailed Mixed Layer Model • Dynamic Ocean Model
Other Schemes • Cyrosphere • hydrologic cycle • albedos • wind and heat • Vegetation • different scales • lack of validation data
AOGCM Problems • Time Scales • Grid Scales • Costs
AOGCM Solutions • Asynchronous Coupling
Conclusion There is a long way to go before we have RELIABLE Models with which to predict CLIMATE and CLIMATE CHANGE …