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Modeling the oceanic thermohaline circulation with STELLA

Dave Bice, Penn State University, On the Cutting Edge collection, Science Education Resource Center at Carleton College

In this activity for undergraduate students, learners build a highly simplified computer model of thermohaline circulation (THC) in the North Atlantic Ocean and conduct a set of simulation experiments to understand the complex dynamics inherent in this simple model.

Activity takes about 2-3 hours. STELLA software licenses are required.

Learn more about Teaching Climate Literacy and Energy Awareness»

ngssSee how this Activity supports the Next Generation Science Standards»
High School: 1 Disciplinary Core Idea, 7 Cross Cutting Concepts, 8 Science and Engineering Practices

Climate Literacy
About Teaching Climate Literacy

Ocean as climate control, oceanic conveyor belt; abrupt changes in thermohaline circulation
About Teaching Principle 2
Other materials addressing 2b
Equilibrium and feedback loops in climate system
About Teaching Principle 2
Other materials addressing 2f
Observations, experiments, and theory are used to construct and refine computer models
About Teaching Principle 5
Other materials addressing 5c

Excellence in Environmental Education Guidelines

1. Questioning, Analysis and Interpretation Skills:G) Drawing conclusions and developing explanations
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G) Drawing conclusions and developing explanations.
1. Questioning, Analysis and Interpretation Skills:B) Designing investigations
Other materials addressing:
B) Designing investigations.
1. Questioning, Analysis and Interpretation Skills:C) Collecting information
Other materials addressing:
C) Collecting information.
1. Questioning, Analysis and Interpretation Skills:F) Working with models and simulations
Other materials addressing:
F) Working with models and simulations.
2. Knowledge of Environmental Processes and Systems:2.1 The Earth as a Physical System:A) Processes that shape the Earth
Other materials addressing:
A) Processes that shape the Earth.
2. Knowledge of Environmental Processes and Systems:2.1 The Earth as a Physical System:C) Energy
Other materials addressing:
C) Energy.

Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

  • Educators will need to review this activity carefully to ensure that students are adequately prepared to use this resource.
  • Instructors will have to develop their own activity assessment, since one is not provided.
  • Instructors may wish to have students look at the CLEAN selected that shows a NASA simulation of the Thermohaline Circulation: http://svs.gsfc.nasa.gov/vis/a000000/a003600/a003658/

About the Science

  • The thermohaline circulation system (THC) of the North Atlantic Ocean is critically important to the climate system since it is involved with the transport of significant amount of heat to high latitudes of the northern hemisphere.
  • This activity describes the construction of and then experimentation with a STELLA model of the THC.
  • The experiments include examinations of the impacts of varying the initial reservoirs, temperature changes and freshwater pulses.
  • The activity will challenge student's expectations that only complex behaviors come out of complex systems and models.
  • The activity is based on the Stommel 1961 paper (Tellus, 8, 224-230) about thermohaline convection. While not current, this activity can foster a fundamental understanding of THC dynamics.
  • Comments from expert scientist: Deals with highly relevant question of how THC might respond in a warming world. Students experiment with combined effects of T and S (and delT and delS), and the model includes exchanges with the atmosphere in addition to mixing. The model is simple, yet complex enough to be challenging.

About the Pedagogy

  • The Activity Description/Activity sheet provides only an indication of the kind of background that instructors will need to make effective use of this simulation activity. The recipe for the simulation model and the various experiments are tersely described and may prove confusing for educators and learning without sufficient preparation.
  • It is evident that this activity is taken largely unedited from an existing course by the authors.
  • Students will require background instruction on systems dynamics, building models in STELLA and the components of a model of the thermohaline circulation system of the North Atlantic Ocean. A full recipe is provided.
  • Students work in groups and are expected to prepare a report on their findings.
  • The solution set page gives important insights into the behavior of the model for assessment purposes.

Technical Details/Ease of Use

Next Generation Science Standards See how this Activity supports:

High School

Disciplinary Core Ideas: 1

HS-ESS2.C1:The abundance of liquid water on Earth’s surface and its unique combination of physical and chemical properties are central to the planet’s dynamics. These properties include water’s exceptional capacity to absorb, store, and release large amounts of energy, transmit sunlight, expand upon freezing, dissolve and transport materials, and lower the viscosities and melting points of rocks.

Cross Cutting Concepts: 7

Patterns, Cause and effect, Systems and System Models, Energy and Matter, Stability and Change

HS-C1.4: Mathematical representations are needed to identify some patterns.

HS-C2.2:Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system.

HS-C2.4:Changes in systems may have various causes that may not have equal effects.

HS-C4.2:When investigating or describing a system, the boundaries and initial conditions of the system need to be defined and their inputs and outputs analyzed and described using models.

HS-C4.4:Models can be used to predict the behavior of a system, but these predictions have limited precision and reliability due to the assumptions and approximations inherent in models.

HS-C5.2:Changes of energy and matter in a system can be described in terms of energy and matter flows into, out of, and within that system.

HS-C7.2:Change and rates of change can be quantified and modeled over very short or very long periods of time. Some system changes are irreversible.

Science and Engineering Practices: 8

Asking Questions and Defining Problems, Developing and Using Models, Planning and Carrying Out Investigations, Analyzing and Interpreting Data, Using Mathematics and Computational Thinking, Constructing Explanations and Designing Solutions, Obtaining, Evaluating, and Communicating Information

HS-P1.4:ask questions to clarify and refine a model, an explanation, or an engineering problem

HS-P2.6:Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems.

HS-P3.1:Plan an investigation or test a design individually and collaboratively to produce data to serve as the basis for evidence as part of building and revising models, supporting explanations for phenomena, or testing solutions to problems. Consider possible confounding variables or effects and evaluate the investigation’s design to ensure variables are controlled.

HS-P4.1:Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

HS-P4.5:Evaluate the impact of new data on a working explanation and/or model of a proposed process or system.

HS-P5.2:Use mathematical, computational, and/or algorithmic representations of phenomena or design solutions to describe and/or support claims and/or explanations.

HS-P6.2:Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

HS-P8.5:Communicate scientific and/or technical information or ideas (e.g. about phenomena and/or the process of development and the design and performance of a proposed process or system) in multiple formats (i.e., orally, graphically, textually, mathematically).

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