Atmospheric methyl chloroform: a leaky water tank example

Robert MacKay
Clark College Physics and Meteorology
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Atmospheric methyl chloroform concentration is modeled as an extension of the generic water tank structure. Simulated and observed concentrations are used to estimate the global atmospheric lifetime of methyl chloroform and its 1989 to 2009 emission history.

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Students in an environmental modeling course who have been introduced to the generic leaky water tank structure.

Skills and concepts that students must have mastered

  • Have reviewed graphing.
  • Are familiar with the notation of the derivative and its graphical interpretation.
  • Have used Stella II software several times (this is a fairly simple model to construct)

How the activity is situated in the course

This is intended as an activity for the 4th or 5th week of 15 week environmental modeling class. A solid introduction to modeling, the Stella II modeling environment, and introductory concepts from system dynamics (equilibrium, time constant, stocks and flows) is assumed.


Content/concepts goals for this activity

  • Be able to model the behavior of an atmospheric trace gas that can be characterized by a single lifetime.
  • Use model and observations to estimate emissions and atmospheric lifetime.
  • Learn basics of least squares comparison
  • Begin to think about how models can help in the development and monitoring of public policy

Higher order thinking skills goals for this activity

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Description of the activity/assignment

Determining whether students have met the goals

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