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Systems modeling presentation
- 1. Systems Thinking – Modeling a System
- 2. A simple example of a dynamic system – a bathtub •The balance between the inflow through the faucet and the outflow through the drain determines how much water accumulates in the tub. Is this system open or closed?
- 3. Examples in the Earth System Inflow (runoff, precipitation) Reservoir (pond) Outflow (stream outlet) https://en.wikipedia.org/wiki/Alpine_Lakes_Wilderness#/media/File:Lila_Lake_26527.JPG
- 4. Examples in the Earth System Inflow (snowfall) Outflow (melting, icebergs) Reservoir (glacier) http://cdn.antarcticglaciers.org/wp-content/uploads/2012/08/fs20093046_fig03.pn
- 5. Examples in the Earth System Reservoir (atmosphere) Atmospheric CO2 760 Gton(C) 60 Gton(C)/year Photosynthesis 60 Gton(C)/year Respiration and Decomposition OutflowOutflow
- 6. Examples in society Inflow (entrance) Outflow (exit) Reservoir (parking lot) https://en.wikipedia.org/wiki/P arking_lot#/media/File:P30300 27ParkingLot_wb.jpg
- 7. Examples in society $$ Inflow (income) $ Outflow (spending) Reservoir (Bank account) https://openclipart.org/detail/231056/bank
- 8. Why use a systems model? • Systems diagrams are useful for showing relationships in a system: • Systems models are useful for quantifying relationships in a system, and allowing system behavior to be explored experimentally: 10 liters 1 liter/minute 1 liter/minute Bathtub
- 9. Systems model of the bathtub •STELLA is a software package that allows the user to build icon-based dynamical systems models •The goal is to take the systems diagram of a bathtub and simulate in a STELLA model •A STELLA model of the bathtub system includes a reservoir for the bathtub, and two flows that represent the faucet and drain Inflow OutflowReservoir
- 10. Unit 3 Bathtub Model Model: icon-based representation of the system Equation: mathematical representation of the system - STELLA does the calculations for us Output: graph of the system model output as it runs - in this case, the change in the water in bathtub with time
- 11. Systems modeling • The bathtub model is simple enough that we could just do the calculation of flows and reservoir size with each time step by hand • BUT, when a system is more complicated, a systems model becomes necessary to keep track of everything • For example, below is a systems model for the Earth’s energy balance (i.e., inflow of energy from the Sun, the Earth reservoir of energy, and outflow of energy back to space) Inflow OutflowReservoir
Notes de l'éditeur
- Instructor – notes for emphasis This is an open system - we are not keeping track of where the water is coming from [source] and going to [sink] The faucet and drain can be adjusted to any flow rate [or flux] we want Even if level of water in the bathtub remains constant, individual water molecules are still moving through the system. This bathtub is a dynamic system because material is flowing through the system and the rates of flow and the amount of water in the tub may change over time Although this is a simple example, there are analogies all around us in the Earth System and society Image created by K. Kreutz
- https://en.wikipedia.org/wiki/Alpine_Lakes_Wilderness#/media/File:Lila_Lake_26527.JPG Creative Commons
- http://pubs.usgs.gov/fs/2009/3046/ http://cdn.antarcticglaciers.org/wp-content/uploads/2012/08/fs20093046_fig03.png Creative commons
- Image by K. Kreutz Data from Kump et al., The Earth System, 2010, Chapter 8
- https://en.wikipedia.org/wiki/Parking_lot#/media/File:P3030027ParkingLot_wb.jpg Creative commons
- https://openclipart.org/detail/231056/bank Creative Commons
- Instructors – notes for emphasis Why do this at all? While generic, the bathtub model can be used to simulate behavior that is applicable to any system in Earth Science or society.