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

3. CTD – Conductivity-Temperature-Depth Recorder
thermistor
CTD – Conductivity-Temperature-Depth Recorder

4. Celsius Temperature = Thermodynamic Temperature – 273.15ºK
(from Pinet, 1998)
Celsius Temperature = Thermodynamic Temperature – ºK
Measured with International Temperature Scale ( ITS-90)
T68 = T90
T68 = International Practical Temperature Scale 1968 (ITPS-68)

5. (from Pinet, 1998)
(NORTHERN HEMISPHERE) 4

6. (from Pinet, 1998)
(NORTHERN HEMISPHERE) 4

7. Pressure = Mass * Gravity / Area
Pressure = Force / Area
Pressure = Mass * Gravity / Area
Mass = Density * Volume
Pressure = Density * Volume * Gravity / Area
Volume/ Area = Depth
Pressure = Density * Gravity * Depth

8. DENSITY VARIES CONINUOUSLY
PRESSURE z
- z Pz
Pz = - g z
DENSITY CONSTANT z1
- z Pz z2 z3
Pz = -Σ13 ng zn
DENSITY STRATIFIED
Pycno-
cline
- z Pz
Mixed
Layer
DENSITY VARIES CONINUOUSLY
WITH DEPTH
Units: N/m2 = Pa
1 m depth ~ 1 db ~ 104 Pa

9. Major Constituents Cl- 18.98/34.4 = 55% Na+ 10.556/34.4 = 31%
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
The MAJOR constituents of seawater are conservative.
Conservative means that they are not affected by chemical or biological processes.
Discuss.
You can mix two ocean waters and get a third mixture.
That is a conservative process.
The major constituents are sodium and chloride.
Note that salt is similar to blood. The concentration of salts is nearly the same.
What else is in seawater?
Cl /34.4 = 55%
Na /34.4 = 31%

10. Residence Time = Concentration (mass/vol)/Rate of supply (mass/vol/time)
Residence time is important. The easy way to calculate it is to divide the amount of the material (say lithium) in the ocean by the rate that it is coming in from the rivers.
Of course sodium and chloride stay around a long time. But not long on geological time scales.
Many are reactive and don’t stay in the ocean very long. Calcium builds shells.
Barium, cobalt, chromium and aluminum react and precipitate.
Strontium is absorbed along with calcium in shells.
The ocean mixes on scales of 100 to 1000 years but the major constituents are around for millions of years.
The ocean is well mixed.

11. 8.

12. Reference Composition Salinity SR does have units!
TEOS-10 Manual
“Thermodynamic properties of seawater are more accurately represented as functions of SA than of SP.”
Reference Composition Salinity SR does have units!
SR = /35 Sp (g/kg)

13. ----- cannot be measured in practice.
Absolute Salinity SA : “ratio of the mass of dissolved material in sea water to the mass of sea water.”
----- cannot be measured in practice.
Reference Salinity SR gives our best estimate of SA
SA = SR + SA
SR = /35 Sp (g/kg)
(From TEOS-10 Manual)
Still much work to be done on SA

14. Where do the Salts come from?
Let’s go over the sources of the salts.

15. high
temperate
subtropical 7.
(from Pinet, 1998)

16. TEMPERATURE
Salinity
Temperature 37 34 31 30 20 10

17. density anomaly (kg/m3)
WATER DENSITY
density anomaly (kg/m3)
Equator
Density Profiles in the Open Ocean
1000
Tropics
depth (m)
2000
High Latitude
3000
4000
Density Anomaly σt = Density
Specific Volume = Inverse of Density

18. 11.
(from Pinet, 1998)

19. TEOS-10

20. TEOS-10

21. 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
-1.33
Now we see how the salt content changes the properties of seawater.
Recall how salt ions sit amongst the water molecule clusters as the salts are hydrated.
Freezing point depression: typically salt water freezes at -1.9C. Salt keeps the molecules from forming the crystal lattice until enough heat is removed to slow things down.
Density: The salts are heavier than water molecules and thus the salty water is heavier. The salts cause the temperature of maximum density to be decreased. Above salinity 27 seawater density decreases with increasing temperature. What does this mean to lakes and oceans?
A lake turns over as it freezes
The ocean remains stratified as it freezes
24.7
(from Pinet, 1998)

22. 90 % of Ocean Water Greater influence of salinity on density
Mean T & S for World Ocean
Greater influence of salinity on density

23. Sound Speed: C = 1449 + 4. 6 T – 0. 055 T 2 + 1. 4 (S – 35) + 0
Sound Speed: C = T – T (S – 35) D (m/s)
Cair = 330 m/s ~ 660 kn

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

26. k = vertical attenuation coefficient (m-1)
clear ocean water
turbid
coastal
water
Light Penetration in Sea Water
Iz = Io e –k z
k = vertical attenuation coefficient (m-1)
(fraction of that entering at the surface)

27. Water absorbs reds and oranges (long wavelength light – warm colors)
scatters blue (short wavelength light – cool colors)

28. Coriolis Deflection Animated illustration 1 Animated illustration 2
Animated illustration 1
Animated illustration 2

29. Atmospheric Processes
Air pressure differences create the global wind field.
Coriolis deflection causes winds to blow in the direction in which they do.
Air Pressure: P = density x g x height

30. Equatorial atmospheric circulation – Walker cell
isobaric
surfaces
Walker
Cell
Strong convection in W Pac, Congo, Amazon

31. Meridional air circulation cells
Trades - return flow in the Hadley/Walker cell system
Meridional air circulation cells

32. Note the strong convection in: a) the western tropical Pacific, b) along ~5-10ºN (ITCZ), and c) along º (Polar Fronts)

33. Rotating Globe

34. Global Wind Fields

36. Global Air Pressure Distribution
Icelandic Low
Aleutian Low

37. Summer/Winter Pressure Variations
Permanent Highs over Indian S Pac, S Atl,
Permanent Low over Southern Ocean
High over N Pac and N Atl modified by Aleutian Low and Icelandic Low

38. Global wind speeds

39. Seasonal Variations of ITCZ and generation of Tropical Depressions

40. Seasonal excursion of the ITCZ
Mats Halldin

41. SE trades become SW when crossing the Equator to the N (Coriolis)
This generates a Tropical Depression

43. Location of formation of tropical storms/hurricanes
Steered by oceanic tropical anticyclone – Trades / Westerlies