Analysis Tools for Numerical Simulations of Estuaries

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Analysis Tools for Numerical Simulations of
Estuaries

• Parker MacCready
• University of Washington
• NANOOS PI Meeting 2/1/2006 Newport, OR

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Motivation

• The initial scope of my part of the NANOOS Pilot
  was to develop quality metrics.
• This is relatively straightforward, and is
  already being done as part of the CORIE system.
• gt I have put my effort into developing useful
  metrics that
• (1) We are able to compute because we have the
  full 3-D fields calculated by the numerical
  simulations
• (2) Give insight into the function of the system

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Progress

• Metrics related to time-dependence (adjustment
  time and sensitivity) developed (theory, a simple
  numerical model, and comparison with
  observations) and submitted to J. Phys. Oceanogr.
• Metrics related to flow of mechanical energy in
  the system developed and presented as a talk at
  ERF 2005.
• Draft write-up of Analysis Tools done in
  December 2005. I am now working with Antonio and
  his Masters student on implementing them in the
  CORIE system.

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Quasi-steady response of the length of the salt
intrusion to varying QR

• This is a classical metric, which we know
  observationally for a number of estuaries
• It can be distilled into the exponent in a power
  law relating the length of the salt intrusion to
  the river flow

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Consider the effects of time-dependence

• Estuaries take time to adjust to their forcing
  conditions.
• The ratio of the adjustment time to the forcing
  timescale can strongly affect whether or not the
  estuary feels the effects of a given change in
  forcing
• Example Stratification is generally MORE
  sensitive than you would predict from a
  quasi-steady theory, whereas the length of the
  salt intrusion is LESS sensitive.

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The Mechanical Energy Budget

• By evaluating terms in the volume-integrated,
  tidally-averaged energy budget, we may better
  understand how an estuary works
• In this example the long residence time is a
  consequence of the huge reservoir of potential
  energy stored in the length of the salt intrusion

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Conclusion

• The advent of realistic 3-D numerical simulations
  of estuarine circulation and salinity structure
  (and eventually ecosystems) gives us much greater
  ability to develop metrics to describe and
  compare these systems.