1 / 12

Using Modelling to Address Problems

Using Modelling to Address Problems. Scientific Enquiry in Biology and the Environmental Sciences Modelling Session 2. Seminar 2 outline. What is the process for building a model? How are models applied in problem solving situations? How is uncertainty quantified and attributed?

chaserobert
Download Presentation

Using Modelling to Address Problems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Using Modelling to Address Problems Scientific Enquiry in Biology and the Environmental Sciences Modelling Session 2

  2. Seminar 2 outline • What is the process for building a model? • How are models applied in problem solving situations? • How is uncertainty quantified and attributed? • What parts of the model are critical controls on model behaviour? • How can data and models be integrated?

  3. Constraints on model structure • Realism - the degree to which model structure mimics the real world • Precision - the accuracy of model predictions (output) • Generality - the number of systems and situations to which the model correctly applied

  4. The process of modelling 1. Objectives: identify the system, the questions, the stopping rule, ultimate goals 2. Hypotheses: develop specific hypotheses and graphical description of the model 3. Mathematical formulation: convert qualitative hypotheses into mathematical equations 4. Coding and verification: convert equations to code and develop numerical framework 5. Initial conditions, parameters and calibration: set start conditions, calibrated rate constants 6. Analysis and evaluation: execution, qualitative and quantitative checks, falsification

  5. Principles of qualitative formulation • Identify state variables • Identify flows among state variables • Identify the controls on flow rates • Identify auxiliary and driving variables • Identify the time-step

  6. The modelling process • Calibration – determination of model parameters • Corroboration - testing model output • Sensitivity analysis – how do inputs relate to outputs • Residual analysis - what might explain model failure

  7. Litterfall/ sedimentation Photosynthesis Combustion Respiration The Global Carbon Cycle – a simple model Fossil Fuels (7 per yr) & volcanoes Atmosphere (750) Vegetation (700) Ocean (50 in surface, 40000 at depth) Soils (1500) Sediments 75,000,000

  8. Litterfall/ sedimentation Photosynthesis Combustion Respiration The Global Carbon Cycle – a simple model Fossil Fuels (7 per yr) & volcanoes Atmosphere (750) Vegetation (700) Soils (1500) Influence Global temperature

  9. Specifying equations • Photosynthesis is a saturation equation on atmospheric CO2 concentration • Respiration is an exponential function of temperature • The pre-industrial C cycle is calibrated at a steady-state • But the parameters are not well known…

  10. The global C cycle “The breathing forest model” www.sei.se/forests/index.htm

  11. FUSION ANALYSIS ANALYSIS Complete with clear confidence limits & capable of forecasts Data Assimilation MODELS MODELS -Capable of interpolation & forecasts -Subjective & inaccurate? OBSERVATIONS OBSERVATIONS -Clear confidence limits -Incomplete, patchy -net fluxes

  12. Seminar 2 summary • The importance of functional forms in model behaviour • Parameter uncertainty can be translated into predictive uncertainty • Models can be used as management tools for control • Data assimilation is a process for optimally combining models with observations

More Related