Quaternary Environments Paleoclimate Models

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Quaternary EnvironmentsPaleoclimate Models
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Types of Models

• Simplify a system to its basic components
• Types of Models
• Physical Models
• Globe
• Statistical Models
• Regression Equations
• Conceptual Models
• Flow chart
• Computer Models
• GCMs
• Test Hypotheses

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Types of Models

• Energy Balance Models (EBMs) Surface
  temperature as a result of energy balance
• Zero-Dimension Whole Earth
• One-Dimension Earth in zonal bands with
  latitudinal heat transfer
• Two-Dimensions Lat/Long or Latitude/Altitude
  changes
• Statistical Dynamical Models (SDMs)
• Use parameterized input equations to describe
  changes through time
• Radiative Convective Models (RCMs)
• Radiative processes in vertical columns
• General Circulation Models (GCMs)
• Use physical laws to drive all changes
• Coupled Ocean-Atmosphere GCMs

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Statistical-Dynamical Model of variations of
Northern Hemisphere ice volume over the last
200,000 years forced by CO2 and Insolation
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Schematic Diagram of atmosphere and ocean
computational boxes in a coupled GCM
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Levels of Complexity and Coupling of
Ocean-Atmosphere Models
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Problems With Current Models

• Expense and Time
• Resolution
• Unknown Quantities
• Cloud cover and feedback
• Difference in response times between various
  components of the model
• Lacking land surface, cryosphere, biogeochemical
  cycles, and biome components
• Climate System Models (CSMs) being developed

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http//www.cru.uea.ac.uk/cru/info/scen/
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Estimated Response and Equilibrium Times for
Different Components of the Climate System
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Model Experiments

• Are changes in orbital parameters enough to cause
  a glacial event?
• Insolation as an input
• Also needed increased cloudiness, increased soil
  moister, a shallow mixed layer in the ocean, and
  lower CO2
• Feedbacks include increased sea ice, lower SSTs
  in summer, and presence of permanent snow cover
  on land

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Difference in Solar Radiation at the Top of the
Atmosphere 115 kya
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Modeled Snow Depth in August for 115 kya
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Input Parameters for COHMAP Simulation
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Output from COHMAP, Split Jet Stream During LGM
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Modeling Forward

• Models can be tested against paleorecords then
  these models can be used to predict future change
• Multiple model outputs to estimate future change

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http//www.cccma.bc.ec.gc.ca/models/cgcm2.shtml
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Two Environment Canada models showing change from
1971-1990 to 2041-2060. Differences are based
on a change in the depth and vigor of vertical
mixing in the Southern Ocean
http//www.cccma.bc.ec.gc.ca/models/cgcm2.shtml
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Scaling down from a GCM through a Regional
Climate Model to the landscape
Climatic Research Unit, University of East
Anglia http//www.cru.uea.ac.uk/
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