instrumentation ctd dissolved oxygen sensor adcp/ current meters oxygen titrations

Instrumentation CTD Dissolved Oxygen Sensor ADCP/ Current Meters Oxygen Titrations Nutrient Concentrations

Circulation and Chemical Tracer Distribution Physical Oceanography Chemical Oceanography

UnitsTemperature: °C

Salinity: no units; defined by 1978 Practical Salinity Scale (PSU)

Pressure: db (decibars)Density

Density (ρ) is a function of T, S, and pρ(4°C, 0, 1 atm) = 1 g cm-3 = 1000 kg m-3

Potential Density of Seawater (corrected for compressibility) ranges from 1022 kg m-3 to 1028 kg m-3 in the open ocean

Sigma Theta (σθ) = ρ(T, S, 1 atm) - 1000 [kg m-3]

We prefer concentration Units of mol/kg

Dissolved Oxygen Units??Puget Sound Scientific Literature:

mg/L, mg-at/L, mL/L, μmol/kgConversion Factors:

1 mole O2 = 32 g O2 = 22.414 L O2 = 2 g-at O

1 L seawater = 1000 cm3 = (0.001 m3)×(density of SW)

Density of SW [kg/m3] = 1000 + sigma theta

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

Puget Sound is an estuary; it is connected to the Pacific Ocean through the Straits of Juan de Fuca.

Coastal Plain or Drowned River Valley Estuary

Fjord estuaries

– Sill blocks exchange of deep water with ocean Little water movement below sill depth

Strong vertical stratification

Fig 12.35

Solid = SurfaceDashed =

Deep

Schematic Diagram of the Flow in Puget Sound

Estuarine Circulation:

Surface Outflow,Deep Inflow

Driven by river input,mixing, and deep water intrusions

Port Susan

Saratoga Passage

WHIDBEY BASIN

Admiralty Inlet

PROCESSES THAT CONTROL CIRCULATION:--Wind Forcing--Density Stratification

Freshwater inflow at the surface--Tides--Flushing events from the open ocean

Stratification

How does it change from rivers to Main Basin?How does change in stratification affect biology?

Measured Currents are dominated by the tides Estuarine flow revealed only when tides are

removed

Tides ≈ 5-10 × Strength of Estuarine Flow

Current Meter Measurements in the Main Basin -- Averaged over the interval indicated -- With the Tidal currents removed

Level of no motion?

Episodic Intrusions of Deep Water

Numerical Modeling

20 layers350-m resolution in Puget SoundRiver flow - 15 major river, USGSAtmosphere - 6-hour avg from MM5Eight tidal components

Water Residence Times

Box Model(1992-2001)

Numerical Model(2006)

Cycles of Phosphorus, Nitrogen, Carbon, Oxygen and Silica in Puget Sound waters

Tracers of Biological Production and Respiration

REDFIELD RATIOS: ∆P : ∆N : ∆C : ∆O2 1 : 16 : 106 : -153

For diatoms: NO3- : Si ratios: ∆N : ∆Si 1 : (1-3)

Dissolved Inorganic Phosphorus, DIP vs Dissolved Inorganic Nitrogen, DINIn the Ocean

REDFIELD STOICHIOMETRY OF LIFE: P : N : C : O2 = 1 : 16 : 106 : 153

Sections of Oxygen, Phosphate, and Nitrate in Whidbey Basin, Oce 220, 2010

O2 (μmol kg-1)

PO43-

(μmol kg-

1)

NO3- (μmol kg-

1)

Nitrate : Phosphate ratios in Port SusanCompilation from recent data (Oce 220 ,

2010)

AOU (Apparent Oxygen Utilization) = [02

sat] –[O2]

RATES: NET OXYGEN PRODUCTION -- PHOTOSYNTHESIS Oxygen Supersaturation in Puget Sound Surface waters Oce 220 2010

( Percent Supersaturation)

RATES OF NET BIOLOGICAL OXYGEN PRODUCTION = ∆O2/ ∆C (153/106) X NET CARBON PRODUCTION (NCP)

OXYGEN FLUX TO THE ATMOSPHERE ~ NET BIOLOGICAL O2 PRODUCTION FO2 = - GO2 {[O2]-[O2]sat}

{[O2]-[O2]sat}The Gas Exchange Mass Transfer Coefficient, G, is a function of wind speed

Rates of Respiration in Waters Below the Surface

Oxygen Utilization Rate (OUR) = Respiration Rate

= AOU / t

t = time since water was at the surface

In Whidbey Basin deep water

t = time since water came into the basin from outside

RATES: NET O2 CONSUMPTION-- RESPIRATION

Knudsen’s Equations

Water Balance:Tin + R = Tout

Salt Balance:SinTin = SoutTout

Solve for Tout:

Tout = R×Sin/[Sin - Sout]

Can add temporal variability, mixing between layers

Main Basin