1. LAB 5: “The Puget Sound Model” Marine water dynamics PRISM OR, WHAT GOES AROUND COMES AROUND (AND DOWN AND UP)

2. 2 The model was constructed in 1950 with funds provided by the Office of Naval Research and under the direction of Professor Clifford A. Barnes to investigate the tidal currents in Admiralty Inlet. The extreme complexity of tidal flow in this area makes a detailed understanding of their characteristics very difficult, if not almost impossible, by field observations alone. A physical model was considered to be the most appropriate method for obtaining the desired information, provided that acceptable representation could be achieved. Prior to the start of construction of the present model, a detailed theoretical study was made to investigate suitable model scales. These studies resulted in selection of a horizontal scale of 1:40,000 and a vertical scale of 1:1,152. From these two scales all others are derived by mathematical relationships. The model basin was formed by making a concrete casting from hand-carved wood patterns. Charts of the area were contoured and the contours transferred at the proper scale to pine boards planed to a thickness corresponding to the contour intervals... The tide computer constructed for the model is the Kelvin type

3. 0 meters 200 meters Puget Sound is deep (and shallow), with strong tides, but sills too Puget Sound is deep (and shallow), with strong tides, but sills too Hood Canal Whidby basin South Sound Main Basin

4. What is below the surface ?

6. river ocean What is below the surface ?? Buoyant river water flows out of an estuary on surface, dense ocean water flows in at depth, but there is mixing, and sills cause “reflux” of water back in to an estuary. Thomson, 1994 1 3 2 4

7. 0 meters 200 meters Puget Sound is fjord-like; a glacial-cut estuarine system It is deep Its nearshore is narrow Newton, Stormer, UW-COFS; Data source: NGDC 1. Bathymetry

8. Water Movement – 2x tides (24 hours 50 minutes) 2. Type of Tide Within Puget Sound, tides are the mixed type, having two highs and two lows each tide day. Heights of the low water generally have the greater variability. Thus each tidal day there occurs a Higher High Water (HHW), a Lower Low Water (LLW), a Lower High Water (LHW), and a Higher Low Water (HLW). Diurnal ranges vary between Spring tides (larger tide ranges) and Neap tides (smaller tide ranges) over a period of 14.3 days, but never exactly repeat. The closest repetitive cycle is approximately 18.5 years, the period of the revolution of the Moon's nodes. Range of Tide The range of tide varies within the system, nearly doubling over the distance from Port Townsend to Olympia. Tidal range variation is the result of the effect of bathymetry, length of the system, and configuration of the basins and interconnecting channels. The Diurnal Range is the difference between HHW and LLW, generally given as the mean difference.

18. LocationTime Difference from Port Townsend (minutes later) Tidal Range (feet) High TideLow TideMeanDiurnal Port Townsend- 5.18.3 Union, Hood Canal 37528.011.7 Seattle48 7.611.3 Bremerton55608.011.7 Tacoma55548.111.8 Olympia799410.514.4 Shelton12014210.614.2 Everett39377.411.1 Cornet Bay63766.610.2

19. WARM COLD temperature salinity determine density FRESH SALTY + less dense more dense “thermocline” or “pycnocline” 3.

20. WARM FRESH COLD SALTY “stratified” “mixed” Density structure can be two different ways:

21. incoming salt water bottom current upwelling river or freshwater input Net Circulation Puget Sound receives a volume of fresh water each year from river discharge, amounting to about 20% of its total volume. The strong tidal currents and turbulence mix the fresh water and seawater. The inflowing river water must escape to the ocean and in doing so, as a result of mixing, carries about nine or ten times its volume of seawater with it. To compensate for the loss of salt and seawater, and to maintain the salt budget, there is an inflow of more saline water from the Strait of Juan de Fuca. The flow balance is thus: 9 parts salt water inflow + 1 part river runoff = 10 parts mixed outflow. Because the mixed water is of lower salinity and therefore of lower density, a net outflow occurs near the surface and a net inflow at depth. A

22. Puget Sound circulation is retentive TacomaStrait of Juan de Fuca Sill

23. 23 Stratification patterns in Puget Sound: 2007 Puget Sound Update, Data source: Ecology/PSAMP

24. 24 fast medium slow medium slow very slow Residence Times (relative)

25. Lo nutrientHi oxygen Phytoplankton present Hi nutrientLo oxygen No phytoplankton And more things vary than just temp. and salinity: Phytoplankton present No phytoplankton { CO 2 + H 2 O C(H 2 O) + O 2 } sunlight nutrients Photosynthesis Respiration Effluent

26. PNW estuaries have strong influence from climate Global influence on: ocean conditions watershed conditions local weather NASA SeaWiFS Image 4.

27. Puget Sound is the only fjord-like estuary that functions with all of these attributes, and that supports intensive human and urban development, in the world.