Hierarchy of atmospheric models

1. Hierarchy of atmospheric models • Considerations: • Purpose • Speed v. Complexity Process Models Limited-Area Models Global Models turbulence balance weather systems regional climate climate states paleoclimate research hurricane intensity seasonal forecasts hurricanes short-term weather global warming climate extremes forecast Ooyama 2001 Fig 8; http://www.ucar.edu/news/releases/2005/wrf.shtml; http://en.wikipedia.org/wiki/Global_climate_model

2. Hierarchy of atmospheric models • Considerations: • Purpose • Speed v. Complexity Process Models Limited-Area Models Global Models turbulence balance weather systems regional climate climate states paleoclimate research hurricane intensity seasonal forecasts hurricanes short-term weather global warming climate extremes forecast Ooyama 2001 Fig 8; http://www.ucar.edu/news/releases/2005/wrf.shtml; http://en.wikipedia.org/wiki/Global_climate_model

3. Hierarchy of atmospheric models • Considerations: • Purpose • Speed v. Complexity Process Models Limited-Area Models Global Models turbulence balance weather systems regional climate climate states paleoclimate research hurricane intensity seasonal forecasts hurricanes short-term weather global warming climate extremes forecast Ooyama 2001 Fig 8; http://www.ucar.edu/news/releases/2005/wrf.shtml; http://en.wikipedia.org/wiki/Global_climate_model

4. Hierarchy of atmospheric models • Considerations: • Purpose • Speed v. Complexity Process Models Limited-Area Models Global Models turbulence balance weather systems regional climate climate states paleoclimate research hurricane intensity seasonal forecasts hurricanes short-term weather global warming climate extremes forecast Ooyama 2001 Fig 8; http://www.ucar.edu/news/releases/2005/wrf.shtml; http://en.wikipedia.org/wiki/Global_climate_model

5. Complexity – Model Resolution • Spatial • Horizontal • Vertical • Temporal x-Δx x x+Δx http://www.progonos.com/furuti/MapProj/CartIndex/cartIndex.html; http://www.climateprediction.net/science/model-intro.php; http://en.wikipedia.org/wiki/Platonic_solid

6. Complexity – Parameterizations • Choices based on purpose, understanding, resolution: • Dry or moist • Friction or no friction • Subgrid processes • Cloud microphysics • Convection • Radiation • Land Surface

7. Example – Global Model • Defining the Purpose • Defining the System • Making Assumptions • Specifying the Equations • Determining Method of Solution • Evaluating Results Example developed from IPCC AR4

8. Global Model – Purpose • Understanding the climate system • Predicting future climate • Evaluating climate sensitivity to anthropogenic forcing (read: human impacts on climate) Can we reproduce the global mean temperature trend over the past decade?

9. Global Model – Defining the system Conceptual model – Energy balance IPCC AR4 WG1 Ch1 FAQ 1.1 Fig 1

10. Global Model – Defining the system Conceptual model – Processes IPCC AR4 WG1 Ch1 FAQ 1.2 Fig 1

11. Global Model – Making assumptions IPCC AR4 WG1 Ch1 Fig 1.2

12. Global Model – Specifying the equationsDetermining method of solution • We already decided that we want to use a Global Model, but which one? • Each has pluses and minuses Acronym Soup NICAM BUGS IGCM AFES CCSM

13. Global Model – Evaluating results • Comparisons: • Theory • Models • Observations Global mean temperature predicted by different models, compared with observations. IPCC AR4 WG1 Ch1 Fig 1.1

14. Questions? http://en.wikipedia.org/wiki/Dymaxion_map