B.18 The Salish Sea Estuarine Circulation: Causes and ConsequencesParker MacCready

The Salish Sea supports a vast ecosystem from phytoplankton to Orcas. These all rely on the presence of nutrients, mainly nitrate.  About 95% of the nitrate entering the Salish Sea  comes from the Pacific Ocean, specifically the waters about 300 meters deep, out beyond the continental shelf. These waters are relatively old, and their chemistry is influenced by long transits from their headwaters in the Equatorial Pacific and north of Japan. Along the way they accumulate nitrate.

This deep inflow is part of the "estuarine exchange flow" or "estuarine circulation" that occurs in the Salish Sea. I'll explain more about how this works in my talk, but for now you should just know that the strength of this exchange flow is about 20 times greater than the sum of all the rivers coming into the Salish Sea, so it is a big deal, and strongly affects everything about water quality here.

Live Ocean created graphI'll present results from a numerical model my group has created, called LiveOcean (see figure). This is a realistic simulation of the whole region, including the Salish Sea and the coastal estuaries. It includes realistic forcing from 45 rivers, detailed winds and atmospheric heating, and tides. It also simulates biological and chemical fields like oxygen and pH. We use the model to help inform oyster growers about ocean acidification, and to help predict the arrival of harmful algal blooms at Washington beaches. Like a weather model, LiveOcean produces a daily forecast, making predictions 3 days into the future every day.

You can see today's predictions and learn more about the model here: http://faculty.washington.edu/pmacc/LO/LiveOcean.html.