Analysis Tools for Numerical Simulations

of Estuaries

Parker MacCreadyUniversity of Washington

NANOOS PI Meeting 2/1/2006 Newport, OR

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.

• => 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

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 Master’s student on implementing them in the CORIE system.

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

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.

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

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.