Puget Sound Oceanography

Puget Sound Oceanography• An introduction by Fritz

Stahr & Christian Sarason

• Outline – estuary definition

– examples - PS, SF Bay, Chesapeake

– tides & other cycles (view model runs)

– exercise with real data

An estuary is...A place where river(s) meets the ocean...

Where the Mississippi River meets the Gulf of

Mexico is not an estuary, though some

side drainage is.

that has surrounding land and a limited opening...

San Francisco Bay where the Central

Valley rivers meets the Pacific is an estuary.

An estuary is...A place where river(s) meet the ocean that has surrounding land and a limited opening...

and where the fresh and salt water mix.Puget Sound is an estuary; it is connected to the Pacific ocean through the Straits of Juan de Fuca.

U.S. Estuary ExamplesChesapeake Bay

Different bathymetry makes for different circulation and mixing

“Standard” deep mouth - e.g., Chesapeake, Tampa & SF Bay

With a sill - “fjord” - e.g., Puget Sound

Different river flow makes for different circulation and mixing

High river flow + weak tides = strong salt wedge

Low river flow + stong tides = well mixed

A quick reminder on tides in Puget Sound...

Each day there are two high and two low tides here, but they’re unequal...we call it “semi-diurnal mixed.”

Every other week, the “phase” or type of tidal range changes between “spring” - large differences between high and low- and “neap” - smaller differences. This plays a role in circulation within the Sound.

A quick reminder on tides in Puget Sound...

Predicitons for Seattle, WA 24 Feb 2004 - 21 Mar 2004

Let’s see some of this in Puget Sound via a

numerical model - courtesy of Mitsuhiro

Kawase, UW and Christian Sarason, OIP