| Summary: | I will give a broad overview of what we know about the tidally-averaged circulation of the Salish Sea. This "estuarine circulation" strongly governs primary production and water quality throughout the system. It brings in nitrate (and low DO) from the NE Pacific shelf break through Juan de Fuca Canyon, and defines the residence times of the many sub-basins. In terms of volume flux it is several tens of times greater than the sum of all the rivers. Our early knowledge from the mid 1900's was guided by CTD casts and use of the Knudsen Relation to estimate a 2-layer transport. Slowly this was supplemented by detailed current meter studies which revealed more complex 3-layer flows, and time dependence on spring-neap and seasonal time scales. Our current knowledge is greatly augmented by detailed 3D numerical simulations, both of the whole Salish Sea and of specific deltas, bays, and sills. Observations with high temporal resolution, such as from the ORCA buoys in Puget Sound have expanded our knowledge of short events such as plankton blooms. In addition long term monitoring programs are just beginning to reveal the extent of inter-annual variability.
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