This refers to a PREVIOUS SW, held February 6, 2016
Please see this page for the most recent Sound Waters information
C.11 Ocean Dynamics and the Salish SeaParker MacCready

This class will be an overview of how water moves around in Puget Sound and the Salish Sea. We will start with the tides, both the patterns of sea surface height and the currents they cause. These currents, especially when they flow through constrictions such as Tacoma Narrows or Admiralty Inlet, can cause intense turbulence. This is important because it works to mix away the "stratification" that is present throughout the Sound. Stratification means that water near the surface is less dense than water at depth. It happens because rivers add light, fresh water and because of surface solar heating. If there were no mixing, the surface waters would be completely separate from the deep waters.

With the addition of tidal mixing, an amazing thing occurs: a persistent inflow of deep water from the ocean comes into Puget Sound, balanced by a persistent outflow of surface waters. This circulation is not apparent to the eye, but it is strong, over 20 times greater than the sum of all the rivers coming in to the Sound. More importantly, it has huge consequences for our water quality and ecosystem.

Almost all of the nutrients used by phytoplankton to grow in Puget sound come from the ocean, brought in by this persistent current. I will give simple explanations of these physical processes and their ecosystem effects, illustrated with visualizations made from realistic computer simulations of our waters. Our newest project is a daily forecast model of Washington coastal waters called LiveOcean. It is like a weather forecast model for the ocean, and you can read more here:

graphic image showing water movement around Puget Sound and the Salish Sea image of surface fields from the live ocean model

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