OCN 201 Seventh Reading Discussion Questions

Water and Seawater III

Trujillo and Thurman - Chapter 5

Surface Salinity Variations

1. Use figure 5.22 to describe the temperature variation pattern for surface waters.

2. Use figure 5.22 to describe the salinity variation pattern for surface waters.

3. Explain why surface water salinity is lower than average (35 ppt) near 60^o N and S. (See figs. 5.22 and 5.23)

4. Explain why surface water salinity is higher than average (35 ppt) near 30^o N and S. (See fig. 5.22 and 5.23)

5. Explain why surface water salinity is lower than average (35 ppt) near 0^o. (See fig. 5.22 and 5.23)

Salinity Variations With Depth

6. Use figure 5.24 to describe the vertical salinity variation with depth in the low latitudes (near 30^o).

7. Use figure 5.24 to describe the vertical salinity variation with depth in the high latitudes (near 60^o).

8. Explain why the largest salinity variations in the open ocean (33-37 ppt) occur in surface waters, whereas deep water is approximately 35 ppt everywhere. (Also see fig 5.24)

Halocline

9. Define halocline and give its depth range. (Also see fig. 5.24 and p. 523)

5.7 How Dos Seawater Density Vary With Depth?

10. Give the density range for seawater in the open ocean.

11. Give the freezing point in degrees centigrade for average seawater.

12. Explain deep-water current formation.

Factors Affecting Seawater Density

13. Describe how seawater density varies with temperature, salinity, and pressure.

14. Explain why temperature and salinity variations affect seawater density more than pressure variations.

15. Explain why temperature determines seawater density for most seawater. (i.e. Why is salinity not more important?)

Temperature and Salinity Variations With Depth

16. Explain why the low-latitude surface waters are relatively uniform down to approximately 300 m. (Also see fig. 5.25a)

17. Describe the low-latitude vertical temperature variation from 300-1000 m. (Also see fig. 5.25a)

18. Describe the low-latitude vertical temperature variation below 1000 m. (Also see fig. 5.25a)

19. Describe the high-latitude vertical temperature variation. (Also see fig. 5.25b)

20. Describe the low-latitude vertical density variation from 0-300 m, 300-1000 m, and below 1000 m. (Also see fig. 5.25c)

21. Describe the high-latitude vertical density variation. (Also see fig. 5.25d)

22. Explain why very cold, winter water easily can sink in the high latitudes.

23. Explain the strong correlation between the temperature and density graphs in figure 5.25.

Thermocline and Pycnocline

24. Define thermocline. (Also see p. 533 and fig. 5.25)

25. Define pycnocline. (Also see p. 530 and fig. 5.25)

26. In which latitudinal region do a thermocline nor pycnocline not form? (Also see fig. 5.25)

27. Explain why surface waters and deep waters generally do not mix.

28. Give the relative densities for each of the three layers in the ocean's density structure: surface water, pycnocline, and deep water.

29. Explain why the surface water commonly is called the mixed layer.