instrumentation ctd dissolved oxygen sensor adcp/ current meters oxygen titrations nutrient...
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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)
DensityDensity (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 Susan
Compilation 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