1. TYPICAL TEMPERATURE PROFILES(from Pinet, 1998)

Thermocline is a range of depths

2. CTD – Conductivity-Temperature-Depth Recorder

thermistor

Celsius Temperature = Thermodynamic Temperature – 273.15ºK

Measured with ITS90

T68 = 1.00024 T90

(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

zgP

6. PRESSURE

z

- zPz

Pz = - g z DENSITY CONSTANT

z1

- zPz

z2

z3

Pz = -Σ13 ng zn

DENSITY STRATIFIED

Pycno-cline

- zPz

MixedLayer

DENSITY VARIES CONINUOUSLYWITH DEPTH

zzz gdzP

0

Units: N/m2 = Pa

1 m depth ~ 1 db ~ 104 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……. = K15 Conductivity of a KCl solution in which the mass fraction of KCl is 0.0324356 at same T and P

If K15 = 1, then the Practical Salinity is 35

S = a0 + a1 K15½ + a2 K15 + a3 K15

3/2 + a4 K152 + a5 K15

5/2

where: a0 = 0.0080a1 = -0.1692a2 = 25.3851a3 = 14.0941a4 = -7.0261a5 = 2.7080Σai = 35.000

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- 18.98/34.4 = 55%Na+ 10.556/34.4 = 31%

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

Where do the Salts come from?

hightemperatesubtropical

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?What would temperature look like?

9. Latitudinal variations in surface salinity

(Pinet, 1998)

TEMPERATURE

Salinity

Temperature

37

34

31

30

20

10

10. WATER DENSITY

dept

h (m

)

density anomaly (kg/m3)23 24 25 26 27

1000

2000

3000

4000

Density Profiles in the Open Ocean

High Latitude

EquatorTropics

Density Anomaly σt = Density - 1000

Specific Volume = Inverse of Density

11.

(from Pinet, 1998)

Equation of State (EOS-80)

Determines water density from T, S, and P

),,(/1),,(/1)0,,(),,( PTSPTSKPTSPTS

22/3)0,,(/1)0,,( DSCSBSATSTS

22/32/3 )()(),,( PNSMPJSISHGSFSEPTSK

A through N are polynomials

T is temperature in oC

S salinity

P pressure in bars

K is the secant bulk modulus (change in volume as pressure is changed)

A B C D

T0 999.842594 8.24493E-1 -5.72466E-3 4.8314E-4

T1 6.793952E-2 -4.0899E-3 1.0227E-4

T2 -9.095290E-3 7.6438E-5 -1.6546E-6

T3 1.001685E-4 -8.2467E-7

T4 -1.120083E-6 5.3875E-9

T5 6.536332E-9

E F G

T0 19652.21 54.6746 7.944E-2

T1 148.4206 -0.603459 1.6483E-2

T2 -2.327105 1.09987E-2 -5.3009E-4

T3 1.360477E-2 -6.1670E-5

T4 -5.155288E-5

H I J

T0 3.239908 2.2838E-3 1.91075E-4

T1 1.43713E-3 -1.0981E-5

T2 1.16092E-4 -1.6078E-6

T3 -5.77905E-7

M N

T0 8.50935E-5 -9.9348E-7

T1 -6.12293E-6 2.0816E-8

T2 5.2787E-8 9.1697E-10

),0,35(

),,(),,(

P

PTSPTS

Specific Volume Anomaly

Check values: 489.1069)1000,5,35(343.1023)0,25,35(

12. Effects of Salinity on the Properties of Seawater

Lowers freezing point

Lowers temperature of maximum density

Lowers evaporation rate

24.7

-1.33

Seawater freezesbefore reachingmax 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

T

1

S

1

Thermal Expansion Saline Contraction

x 10-4 oC-1 x 10-4 S-1

Density changes by 0.2 kg/m3 for a T change of 1oC, 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)                                                               

Depth Salinity In situ  Theta Sigma -t Sigma-Theta

1455 34.58 3.20oC 3.09 27.55 27.56

2470 34.64 1.82 1.65 27.72 27.73

3470 34.67 1.52 1.31 27.76 27.78

4450 34.67 1.65 1.25 27.76 27.78

6450 34.67 1.93 1.25 27.74 27.79

8450 34.69 2.23 1.22 27.72 27.79

10035 34.67 2.48 1.16 27.76 27.79

 

Temperature a water parcel would have if raised adiabatically to the surface

dept

h (m

)

0 1 2 3 4

2000

4000

6000

8000

10000

dept

h (m

) 2000

4000

6000

8000

10000

T σt σΘΘ

0 1 2 3 427.4 27.8 27.4 27.8

Tσt

ΘσΘ

15. Example of in-situ and potential temperature

How do we convert to potential temperature?

)/(104

1021

4p

4

CkgJC

db

C

Cg

pT

dpT

o

o

p

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-situpotential

Effect of pressure on density

PSPT

R

Density Ratio

Relative importance of thermal expansion and haline contraction.

Tells us whether temperature or salinity gradient is most important in stratification

PSPT

R

Example in Easter Island

PC2

1

SOUND SPEED

Sound is a wave that travels efficiently in water at a speed given by thisThermodynamic expression.

Eta is the entropy (normalized energy of the system)

A simpler form of that equation is:

C = 1449 + 4.6 T – 0.055 T 2 + 1.4 (S – 35) + 0.017 D (m/s)

16. C = 1449 + 4.6 T – 0.055 T 2 + 1.4 (S – 35) + 0.017 D (m/s)

Cair = 330 m/s ~ 660 kn

SOFAR Channel and Acoustic Shadow Zone (SOund Fixing And Ranging )

Dep

th (

m)

(From Tomczak’s Web Site)

Light Penetration in Sea Water

Iz = Io e –k z

k = vertical attenuation coefficient (m-1)

k = 0.02

k = 0.2

k = 2clear ocean water

turbidcoastal water

(fraction of that entering at the surface)