In this earlier post, I analyzed tidal water surface elevation data from the NOAA PORTS system from both the Delaware Estuary and the Chesapeake Bay, showing how the two systems react very differently to the tidal forcing at their Atlantic Ocean boundaries.  Animated plots may be even more effective at demonstrating this difference in response.  In the Delaware, the tidal fluctuation is amplified as it is translated upstream, but in the Chesapeake it is dampened.

On January 23rd, you can see the influence of the surge from winter storm Jonas.

This graph was created in R using the animation library.

In a previous post I showed an animated age structure diagram depicting output from a simple population model written in Excel.  Here is another version of that model written in R.  One of the things I like about the R version is that I can post the animated .gif files directly into presentations without having to link to a video hosting site.

In class, I use the changed fertility and death rates to demonstrate the impacts on a population.

After I completed the animated tidal water surface elevation plots for the Delaware Estuary, I looked for other systems with a good set of tidal observation stations.  The Lower Columbia River near Portland, Oregon fit the bill.  Using the NOAA PORTS stations, I set up near real-time animated plots of the Columbia.  Throughout December 2015, this plot showed some interesting results.

At the beginning of December, the observed and predicted water surface elevations are in pretty good agreement.

In 2013, EPA published final national recommended water quality criteria for the protection of aquatic life from the toxic effects of ammonia in freshwater.

http://www.epa.gov/wqc/aquatic-life-criteria-ammonia

These criteria are a function of water temperature and pH, so that the criteria concentration value changes with changing pH and temperature.  Frequently the criteria values are plotted as a slice with one of the two variables held constant.
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