Name_______________________________ Class_____________________ Date

Profile of a Tropical Ocean

Tropical ocean waters have certain physical characteristics, which include temperature and salinity. These two characteristics are influenced by variables that act on the ocean waters. The variables include amount of sunlight received, proximity to the equator, and seasonal effects associated with precipitation and with the discharge of major river systems thousands of kilometers upstream. In addition, temperature and salinity depend on whether the waters are on or below the ocean surface.

Ocean water is 96.5 percent pure water and 3.5 percent dissolved solids, such as salt, and dissolved gases, such as oxygen. The amounts of these dissolved substances remain relatively constant. The salinity of ocean water is measured in terms of parts (solid material) per thousand of ocean water.

Water is considered the universal solvent. It can dissolve most substances, if only in very small amounts. Because some substances are very soluble in water, their concentration in the oceans of the earth is quite high. Approximately 95 percent of the dissolved solids in ocean water are six elements: chlorine, sodium, magnesium, sulfur, calcium, and potassium. The salts in ocean water come from the land and, to a lesser extent, from the evaporation of the ocean water.

Table 1 Salinity in the Warm Tropical Waters Off the Coast of Florida

Depth

(meters)

Parts per Thousand

Minimum

Maximum

0

34.40

35.98

50

34.77

36.20

100

36.20

37.00

150

36.52

37.20

200

36.50

37.10

250

36.40

36.97

300

36.20

36.80

350

35.93

36.60

400

35.67

36.35

450

35.43

36.09

500

35.23

35.78

550

35.07

35.53

600

34.92

35.33

650

34.88

35.22

700

34.83

35.10

750

34.80

35.03

800

34.80

34.97

850

34.83

34.93

900

34.87

34.93

950

34.90

34.97

1000

34.97

35.00

1. What is the minimum salinity level at the ocean surface?___________________________________________

What is the maximum salinity level at the ocean surface?__________________________________________

2. What is the difference in salinity between the minimum and maximum levels at sea level?

3. What is the minimum salinity at a depth of 1000 meters?

How does it differ from the maximum salinity at the same depth?

4. How does the minimum salinity level vary between sea level and a depth of 1000 meters?

What might account for this difference?______________________________________________________

The dissolved gases that warm ocean waters contain are mostly oxygen, carbon dioxide, and nitrogen. The concentration of these gases depends on their concentration in the atmosphere, their solubility, and the temperature and salinity of the ocean water. Table 2 Dissolved Oxygen in the Warm Tropical Waters Off the Coast of Florida

Depth

(meters)

Milliliters per Liter

Minimum

Maximum

0

4.32

5.41

50

4.31

5.25

100

4.18

5.26

150

3.96

4.91

200

3.88

4.71

250

3.90

4.42

300

3.92

4.29

350

3.79

4.25

400

3.50

4.13

450

3.17

3.95

500

3.02

3.71

550

2.92

3.58

600

2.90

3.46

650

2.92

3.24

700

2.92

3.33

750

3.00

3.37

800

3.08

3.50

850

3.25

3.63

900

3.37

3.83

950

3.58

4.28

1000

3.78

4.30

 

The most abundant gas dissolved in ocean water is nitrogen. It is of little importance to the plant and animal life in the earth's oceans, however. Oxygen enters ocean water through the process of photosynthesis, which is carried out by green plants in the ocean. Oxygen also enters the water from the atmosphere and from the rivers emptying into the ocean.

5. In what units is the amount of oxygen in ocean water measured?

6. At which level in the ocean is the amount of dissolved oxygen the greatest?

7. Scan the columns that show the amount of dissolved oxygen in ocean water. What happens to the amount of dissolved oxygen between sea level and a depth of 1000 meters?

8. What might account for this variation in the amount of dissolved oxygen in ocean water?

Solar energy and the properties of water itself determine the temperature of ocean water. Some scientists estimate that absorption of light energy accounts for more than 99 percent of the heat entering the sea. Only a small amount of the heat in the sea comes from the heat in the earth's interior. The amount of heat entering the sea is frequently equal to the amount of heat leaving the sea through the process of evaporation. Winds blowing over the ocean waters also cause the waters to cool off and evaporate. The range of temperatures in the ocean is one of the factors that causes ocean currents and influences the location of marine organisms. The temperature of ocean water, like the salinity, remains fairly constant. This consistency in temperature maintains a balance in marine life and exerts a steady influence along the shoreline of neighboring land areas.
9. What factors influence the temperature of ocean water?

10. How does the temperature of the tropical ocean water influence people living in Florida?____________________

Table 3 Temperature in the Warm Tropical Waters Off the Coast of Florida

 

Temperature (C)

Depth

(meters)

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

0

26.5

26.2

26.2

26.5

27.5

27.9

28.2

28.4

28.8

29.2

28.6

27.6

10

26.5

26.2

26.2

26.5

27.5

27.9

28.2

28.3

28.8

29.0

28.6

27.5

20

26.5

26.2

26.2

26.3

27.5

27.9

28.1

28.3

28.6

29.0

28.6

27.5

30

26.4

26.2

26.1

26.3

27.3

27.8

28.1

28.2

28.6

28.8

28.7

27.7

40

26.3

26.2

25.9

26.5

27.3

27.8

28.1

28.0

28.4

28.8

28.8

27.9

50

26.2

26.2

25.8

26.5

26.7

27.5

27.9

27.9

27.5

28.7

28.4

27.6

60

26.0

26.2

25.7

26.4

26.3

27.2

27.4

27.6

27.0

27.9

27.6

27.4

70

26.1

26.2

25.7

25.8

25.8

26.6

26.9

26.8

26.6

27.0

26.9

27.0

80

25.9

26.0

25.4

25.8

25.3

25.9

26.2

26.0

26.2

26.3

26.3

26.0

90

25.6

25.6

25.5

25.3

25.0

25.4

25.8

25.6

25.5

25.5

25.6

25.5

100

25.3

25.5

25.1

25.0

24.6

25.0

25.2

25.0

25.1

25.5

24.7

24.9

150

22.3

22.9

22.8

22.8

22.0

22.0

22.6

22.0

22.8

22.9

22.5

22.0

200

19.9

20.0

20.1

19.8

19.5

19.7

20.2

20.1

20.0

20.3

19.7

19.5

250

18.0

18.1

18.3

17.9

18.2

17.9

18.1

18.0

18.2

18.4

17.8

17.5

300

16.9

17.0

16.9

16.6

16.5

16.8

16.8

16.9

17.0

17.0

16.9

16.4

350

16.0

15.7

15.6

15.6

14.9

15.5

15.5

15.5

15.8

15.8

15.4

15.1

400

14.3

14.1

14.2

14.4

13.7

14.1

14.2

14.2

14.3

14.1

14.0

14.1

450

13.5

12.9

12.9

13.2

12.3

12.6

13.0

12.9

13.0

13.1

13.0

12.8

500

12.6

11.6

11.8

11.2

11.5

10.8

11.8

11.9

12.0

12.3

11.2

11.8

600

10.0

10.0

9.5

9.4

9.5

9.5

9.5

9.6

9.8

9.8

9.5

10.0

700

7.9

8.0

7.7

7.7

7.7

8.0

7.9

8.0

8.0

8.2

7.9

8.2

800

6.5

6.5

6.6

6.6

6.4

6.6

6.4

6.6

6.7

6.6

7.0

6.9

900

5.8

6.1

5.9

5.9

5.8

5.8

5.9

5.9

5.9

6.0

6.1

6.0

1000

5.2

5.3

5.3

5.3

5.3

5.3

5.2

5.4

5.2

5.3

5.3

5.3

11 00

4.8

4.9

4.9

4.9

4.9

4.8

4.9

4.9

4.9

4.8

4.8

4.8

1200

4.6

4.6

4.7

4.6

4.6

4.5

4.5

4.6

4.5

4.7

4.6

4.5

1 300

4.4

4.4

4.4

4.4

4.4

4.4

4.4

4.4

4.4

4.5

4.5

4.4

1 400

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.3

4.4

4.3

4.3

1 500

4.2

4.2

4.2

4.2

4.2

4.2

4.2

4.2

4.2

4.3

4.2

4.2

 

11. What is the warmest water temperature at sea level?____________________________________________

12. During which month is the surface water of the ocean the warmest?__________________________________

13. What is the greatest range in ocean temperature from the surface to a depth of 1500 meters?

14. During which month(s) is the ocean temperature the coolest?

What would account for these temperatures?

15. What is the average temperature of ocean water at sea level for the year?

16. What factors might account for the fact that ocean temperature does not vary at a depth of 1500 meters?