Puget Sound Oceanography:

Estuarine ProcessesOCN 506C/497C Winter Term 2011Parker MacCready & Julie Keister

http://faculty.washington.edu/pmacc/Est2011/Estuaries2011.html

Class Structure & Expectations

• Lectures MWF 11:30-12:20, OSB 425• Also labs and Guest Experts• This Wednesday: meet at the Old Ocean Building,

ground floor, for the Puget Sound Model• Reading, Discussion, Short Response Essays (1-2

pages) 60%• Final Project – paper (5-10 pages) and

presentation 40%• Undergraduates: no final talk?• There is no final exam

You

• Please email us with (1) a short description of your oceanography background, and (2) a sentence or two about why you are in the class.

• parker@ocean.washington.edu• jkeister@u.washington.edu

Puget Sound Basins, Sills, Rivers, Stratification, and

Mean Currents

Getting to know the Sound

Names• Strait of Juan de Fuca• Admiralty Inlet• Main Basin• Whidbey Basin• Port Susan• Tacoma Narrows• Colvos Passage• South Sound• Hood Canal• Lynch Cove

Names• Strait of Juan de Fuca• Admiralty Inlet• Main Basin• Whidbey Basin• Port Susan• Tacoma Narrows• Colvos Passage• South Sound• Hood Canal• Lynch Cove

Names• Strait of Juan de Fuca• Admiralty Inlet• Main Basin• Whidbey Basin• Port Susan• Tacoma Narrows• Colvos Passage• South Sound• Hood Canal• Lynch Cove

Names• Strait of Juan de Fuca• Admiralty Inlet• Main Basin• Whidbey Basin• Port Susan• Tacoma Narrows• Colvos Passage• South Sound• Hood Canal• Lynch Cove

Bathymetry• The Sound is a system of deep

basins linked by shallow sills• Glacially carved to 600 m• Filled in by sediment to 200m

Cross-sectional shapes• Steep sidewalls (1:5)• Narrow constrictions

Juan de Fuca

Cross-sectional shapes• Steep sidewalls (1:5)• Narrow constrictions

Cross-sectional shapes• Steep sidewalls (1:5)• Narrow constrictions

Watersheds

• Skagit and Snohomish have much of their watershed in the Cascade mountain range

Rivers• Data from USGS gauges• High flow period during the winter due to storms (direct rain)• High flow during the spring due to snowmelt (the “spring freshet”)• Biggest rivers flow into Whidbey Basin (Skagit and Snohomish)• Total for Puget Sound averages 1000 m3 s-1

• Average for the Fraser River (Georgia Strait) is 4500 m3 s-1

Stratification• Density is mostly controlled by salinity• Stagnant basins are more stratified,

especially near the surface

Juan de Fuca

South Sound Whidbey BasinHood Canal

Main Basin

Tidally-Averaged Current

• The observed along-channel flow is mostly “two layered”

• Surface flows out, deep flows in• In and out transport it MUCH greater than

that due to the rivers alone!!!

Juan de Fuca

Main Basin

South Sound Hood Canal Whidbey Basin

There is a strong mean northward flow at all depths in Colvos Passage, balancing net southward flow in East Passage (clockwise circulation around Vashon Island)

BLANK

Map• Cokelet et al. (1990)