1. TYPICAL TEMPERATURE PROFILES (from Pinet, 1998) Thermocline is a range of depths

2. CTD – Conductivity- Temperature-Depth Recorder thermistor

Celsius Temperature = Thermodynamic Temperature – ºK Measured with ITS90 T 68 = T 90 (from Pinet, 1998) 3.

(from Pinet, 1998) (NORTHERN HEMISPHERE) 4

(from Pinet, 1998) (NORTHERN HEMISPHERE) 4

5. Seasonal variability of sea surface temperature throughout the ocean

PRESSURE Pressure = Force / Area Pressure = Mass * Gravity / Area Mass = Density * Volume Pressure = Density * Volume * Gravity / Area Volume/ Area = Depth Pressure = Density * Gravity * Depth

6. PRESSURE z - z PzPz P z = - g z DENSITY CONSTANT z1z1 - z PzPz z2z2 z3z3 P z = - Σ 1 3 n g z n DENSITY STRATIFIED Pycno- cline - z PzPz Mixed Layer DENSITY VARIES CONINUOUSLY WITH DEPTH Units: N/m 2 = Pa 1 m depth ~ 1 db ~ 10 4 Pa

SALINITY Old Definition: “The salinity of a sample of sea water represents the total mass of solid material dissolved in a sample of sea water divided by the mass of the sample, after all the carbonates have been converted into oxide, the bromine and iodine replaced by chlorine, and all organic matter completely oxidized.” Absolute Salinity: “ratio of the mass of dissolved material in sea water to the mass of sea water.” can not be measured in practice. Practical Salinity: is defined in terms of the ratio Electrical conductivity of a sea water sample at 15ºC and one standard atmosphere……. = K 15 Conductivity of a KCl solution in which the mass fraction of KCl is at same T and P If K 15 = 1, then the Practical Salinity is 35

S = a 0 + a 1 K 15 ½ + a 2 K 15 + a 3 K 15 3/2 + a 4 K a 5 K 15 5/2 where: a 0 = a 1 = a 2 = a 3 = a 4 = a 5 = Σa i = Good for 2 < S < 42

Major Constituents The concentrations of these major constituents are conservative. They are unaffected by most biological and chemical processes. This is related to the principle of constant proportion Cl /34.4 = 55% Na /34.4 = 31%

Residence Time = Concentration (mass/vol)/Rate of supply (mass/vol/time)

Where do the Salts come from?

high temperate subtropical 7. (from Pinet, 1998)

8.

(from the Navy Coastal Ocean Model)

High evaporation in subtropics (wind and heat) causes high surface salinity What would temperature look like? 9. Latitudinal variations in surface salinity (Pinet, 1998)

TEMPERATURE Salinity Temperature

10. WATER DENSITY depth (m) density anomaly (kg/m 3 ) Density Profiles in the Open Ocean High Latitude Equator Tropics Density Anomaly σ t = Density Specific Volume = Inverse of Density

11. (from Pinet, 1998)

Equation of State (EOS-80) Determines water density from T, S, and P A through N are polynomials T is temperature in o C S salinity P pressure in bars K is the secant bulk modulus (change in volume as pressure is changed)

ABCD T0T E E E-4 T1T E E E-4 T2T E E E-6 T3T E E-7 T4T E E-9 T5T E-9 EFG T0T E-2 T1T E-2 T2T E E-4 T3T E E-5 T4T E-5 HIJ T0T E E-4 T1T E E-5 T2T E E-6 T3T E-7 MN T0T E E-7 T1T E E-8 T2T E E-10 Specific Volume Anomaly Check values:

12. Effects of Salinity on the Properties of Seawater Lowers freezing point Lowers temperature of maximum density Lowers evaporation rate Seawater freezes before reaching max density (from Pinet, 1998) A lake turns over as it freezes The ocean remains stratified as it freezes

Greater influence of salinity on density 90 % of Ocean Water Mean T & S for World Ocean 13.

14. Effects of Temperature and Salinity on Density Thermal Expansion Saline Contraction x o C -1 x S -1 Density changes by 0.2 kg/m 3 for a T change of 1 o C, and by 0.8 kg/m3 for a S change of 1.

Potential Temperature In situ and Potential Temperature in the Mindanao Trench (from Millero’s home page) DepthSalinityIn situ ThetaSigma -tSigma-Theta o C Temperature a water parcel would have if raised adiabatically to the surface

depth (m) depth (m) T σtσt σΘσΘ Θ T σtσt Θ σΘσΘ 15. Example of in-situ and potential temperature How do we convert to potential temperature?

Γ is the adiabatic lapse rate Γ can also be obtained from Unesco Technical Papers in Marine Science # 44 by Fofonoff and Millard, Unesco 1983 ~0.1º change at 1000 m ~0.3º change at 3000 m Data off Antarctica in-situ potential Effect of pressure on density

Density Ratio Relative importance of thermal expansion and haline contraction. Tells us whether temperature or salinity gradient is most important in stratification

Example in Easter Island

SOUND SPEED Sound is a wave that travels efficiently in water at a speed given by this Thermodynamic expression. Eta is the entropy (normalized energy of the system) A simpler form of that equation is: C = T – T (S – 35) D (m/s)

16. C = T – T (S – 35) D (m/s) C air = 330 m/s ~ 660 kn

SOFAR Channel and Acoustic Shadow Zone ( SOund Fixing And Ranging ) Depth (m) (From Tomczak’s Web Site)

Light Penetration in Sea Water I z = I o e –k z k = vertical attenuation coefficient (m -1 ) k = 0.02 k = 0.2 k = 2 clear ocean water turbid coastal water (fraction of that entering at the surface)