The document discusses several key aspects of ocean temperature: 1. There are three main layers in the ocean - the surface layer, thermocline, and deep ocean. 2. The thermocline experiences rapid temperature changes and is located between 50-500m deep. It is permanent in the tropics and seasonal at temperate latitudes. 3. Ocean currents influence sea surface temperatures and consequently air temperatures over land. Therefore, ocean heat transport patterns impact regional climates.

1. Pressure
• The SI unit for pressure is the K Pa = 10 3
pascals. Previous unit was the Bar. 1 bar = 1
standard atmospheric pressure (sea-level)
Standard Atmospheric pressure = 101.32 Kpa
= 1.01325 bars = 1013.25 mb = 760 mm Hg.
• Important to note: 1 decibar = 10 Kpa =
pressure due to 1 metre depth of seawater.
Why is this useful?

2. Temperature
1. Main source is Sun
The Ocean can transfer large amounts of heat with little
temperature change due to water’s high specific heat
capacity and high latent heats
2. Gas vents at the ocean bottom
Three layers exist in the ocean
1.The surface layer
2. Thermocline
3. The deep ocean

3. Water molecules in different states of
matter
Fig. 5.5

4. The surface layer
1. Variation mainly with latitude
2. Average temperature is 17o
C
3. Polar seas -20
C and Persian Gulf (Low latitude) 36o
C
4. Ocean water freezes at -1.94o
C when salinity is 35
ppt
5. In summer surface temp is higher and the mixed
layer is shallower in winter surface temp is lower
and mixed layer deeper

6. Thermocline
Rapid or sudden change in temperature in
vertical direction.
Mainly between 50 m to 500 m
1. Permanent in the tropics
2. Seasonal at temperate latitudes i.e. present in
summer and missing in winter
3. Absent in the polar waters

7. The deep ocean
1. 90 % water belong to this layer
2. Is not well mixed ,mainly made up of
horizontal layer of equal density.
3. Temperature ranges from 0-3o
C
Average temperature of the ocean is 3.8o
C

8. Thermocline

10. Wind

11. Temperature degree C
Most of the ocean is cold

14. Thermocline

15.  permanent
in the tropics;
 seasonal at temperate
latitudes, i.e., present
in summer, missing in
winter; and
 absent in the polar
waters.
Therefore, thermocline (i.e.,
the inflection point in
temperature-depth graph)
is ...
Depth
Temperature
Tropical
all year round,
in summer at
temperate
latitudes.
Polar latitudes all
year round, in winter at temperate
latitudes

18. Temperature- Bay Of Bengal

19. Indian Ocean-Temperature Profile

21. Annual cycle of SSTin the Indian Ocean-South Asia region

23. Surface Temperature-World Ocean

24. 24
Effect of Ocean Heat Transport
Pattern of currents flow impacts sea surface
temperatures and, as a result, air temperatures over

25. 25
Equatorial Pacific: Sea Surface Temperature
(SST)

26. Wind-driven upwelling keeps the SST low at eastern boundaries

27. Equatorial Ekman upwelling keeps the SST low right along the equator

28. Ocean temperature -August

29. Ocean temperature-February

30. Fig. 5.6

31. Latent heat serves as a thermostat
• water has higher latent heat of fusion and latent heat of
vaporization than almost any other substance
• ice melting consumes heat in summer and freezing releases
heat in winter--reduces seasonality
• vaporization/evaporation consumes heat in the tropics and
condensation releases heat at higher latitudes--poleward
heat transport
• Earth’s surf. temp (-90 to 58°C, -2 to 32 over ocean) is
near 0 to 100°C

32. Heat (calories)
0 200 400 600 800
This is the
temperature
range for
liquid water
0
150
50
100
-50
Heat is the energy needed to change the temperature of a
body or material (e.g., 1 calorie is the heat needed to change
the temperature of 1 gram of water by 1°C)
Temperature(°C)
Temperaturemeasuresthethermal
stateofmatter
Heat versus Temperature
• Heat, the energy needed to change the temperature of a body, can be specific (i.e.,
temperature change at constant phase or state) or latent (i.e., state or phase change at
constant temperature).
A
1. Start with 1 g
of ice at -50°C
B
2. 25 cal of heat will change it
to 1 g of ice at 0°C = ½
× 50°C×1g (Specific Heat)
cal
g°C
C
3. 80 cal of heat will change it from 1 g ice at 0°C
to 1 g water at 0°C, i.e., 80 ×1g (Latent Heat)cal
g
D
4. 100 cal of heat will change 1 g
water at 0°C to 1 g water at 100°C
= 1 ×100°C×1g (Specific Heat)cal
g°C
E
5. 540 cal of heat will change 1 g water
at 100°C to 1 g water vapor at 100°C
= 540 ×1g (Latent Heat)
cal
g
F
6. 25 cal of heat will change 1 g water vapor
at 100°C to 1 g water vapor at 150°C
= ½ ×50°C×1g (Specific Heat)cal
g°C
• This example shows how much heat is needed to
change the temperature of 1 g ice at -50°C to 1 g
Water vapor at 150°C.
• The following changes
occur in this process
− ice from -50°C to 0°C (this
involves specific heat)
− ice to water at 0°C (this involves
latent heat)
− water from 0°C to 100°C (this
involves specific heat)
− water to water vapor at 100°C (this
involves latent heat)
− water vapor from 100°C to 150°C
(this involves specific heat)
Let us use the following constants:
Specific Heat = 1 for water and
½ for ice/vapor
Latent Heat = 80 cal/g to melt ice
540 cal/g to boil water
cal
g°C
cal
g°C

33. http://pubs.usgs.gov/gip/deserts/what/world.html
Deserts tend to cluster about 30º North and South
latitudes, towards the western margins of land.

34. Tropical cyclones develop in the hot, humid air over
a sea surface exceeding 26°C in temperature.