Oceanography Exam II Study Guide

Seawater Properties, Atmosphere and Ocean Circulation

Exam Study Strategies

You will need to be able to answer the following questions in order to correctly answer all the multiple choice and matching questions on the midterm exam II.  Some questions (as noted) can be answered most easily with a drawing or diagram. Be sure to LABEL the important parts of your diagram.  Drawing and labeling diagrams and creating “concept maps” are very effective means of remembering and understanding information, particularly science material.  Terms highlighted in red are extra important to know

1.    What is salinity? How is it measured?

2.    List the two ions with the highest concentrations in seawater. Indicate which ion is a cation and which is an anion. Which salt consists of a combination of these two ions (spell out the name, not just the chemical formula)?

3.    Explain what oceanographers mean when they say that a dissolved ion or salt is conservative in seawater.

4.    Give an explanation for the observation, based on evaporite composition, that sea salt concentration and composition have been nearly constant for about the last 1 billion years.

5.    Why are oxygen concentrations higher in ocean surface waters and lower in the deep ocean?

6.    Why are carbon dioxide concentrations lower in ocean surface waters and higher in the deep ocean?

7.    What are nutrients? Give the names of two nutrients and briefly describe their importance in the ocean.

8.    The energy that the Earth receives from the sun is returned to space by two processes, reflection and re-radiation. Describe, briefly, what happens to the sun's energy when it is reflected and when it is re-radiated.

9.    In the heat budget of the Earth, which two things must balance (or be equal to one another)? What would be the consequence if this balance did not exist?

10.  Why are the equatorial regions of the Earth, on average, hotter than the polar regions?

11.  How does evaporation of water from the oceans result in a transfer of heat to the atmosphere?

12.   Why is carbon dioxide called a "greenhouse gas"?

13.   Why is the concentration of carbon dioxide in the Earth's atmosphere increasing?

14.   It is difficult for scientists to predict how much the Earth's climate will warm, if the concentration of carbon dioxide in the Earth's atmosphere doubles over the next 50 years. Describe one of the reasons for this difficulty.

15.   Why is the salinity of ocean water greater near 30° N than it is near 60° N latitude?

16.   List two processes that increase the salinity of seawater, and two processes that decrease the salinity of seawater.

17.   List two properties of water that affect water density, and, for each, indicate whether density would increase or decrease if that property increased.

18.   Define the terms thermocline and halocline, and pycnocline.

19.   What condition exists when a water column is unstable? Briefly describe one way in which a water column can become unstable.

20.   Define thermohaline circulation.

21.   In which regions of the ocean do deep and bottom waters form? Why is the formation of deep and bottom waters confined to these regions?

22.   A hypothesis has been proposed that states there is a link between the climate of northern North America and Europe (especially ice ages) and the rate of formation of North Atlantic Deep Water. How could North Atlantic Deep Water formation rates affect climate?

23.  Oceanographers say that the deep and bottom waters of the North Pacific Ocean are "old". Why are these waters said to be old?

24.  Define the term water mass.

25.  Explain why a parcel of air which was originally moving directly northward from the equator is displaced to the east, so that it travels to the northeast of its original position. (Note that it is not sufficient to name the effect responsible (Coriolis effect); you must explain what causes this effect (Coriolis effect)).

26.   Unusually large amounts of rainfall occur near the equator. Why?

27.   Between the equator and 30° N, the winds generally blow from the northeast (the Northeast Trade Winds). How do atmospheric convection and the Earth's rotation produce this wind pattern? A diagram may be helpful in answering this question.

28.   Between 30°S and 60°S latitude, the winds generally blow from the northwest (the Westerlies; this wind band includes the "Roaring Forties" and "Furious Fifties" of sailors' lore). How do atmospheric convection and the Earth's rotation produce this wind pattern? A diagram may be helpful in answering this question.

29.   Why is low atmospheric pressure generally found over the oceans of the Northern Hemisphere in winter?

30.   Why do winds in the Northern Hemisphere generally blow counterclockwise around low pressure areas? A diagram may be helpful in answering this question.

31.   What causes the wet, or summer, monsoon found along the west coast of India ? How is this related to the onshore breeze that often occurs in coastal areas during the afternoon?

32.   Although El Niño was first noted along the west coast of South America , it is actually a global phenomenon. What are 3 unusual ocean or weather conditions associated with El Niño, either in the eastern tropical Pacific or elsewhere?

33.   Why do hurricanes form only in the tropics?

34.   What is the Ekman Spiral? How is it related to Ekman Transport? (A diagram may be helpful in answering this question.)

35.   How does Ekman Transport cause coastal upwelling? (A diagram may be helpful in answering this question.)

36.   What is an ocean gyre?

37.   What are eddies? How do they form?

38.   Define the terms divergence, convergence, upwelling, and downwelling.

39.  Describe how the divergence and convergence of ocean currents can cause upwelling and downwelling, respectively.  

       40.   Describe how prevailing winds blowing parallel to a coastline can cause either, upwelling and downwelling.  

       41.  Define thermohaline circulation, and its role in ocean circulation.

      42. List the five common water masses found in the temperate and tropical latitudes.   

      43. Illustrate a general temperature-salinity (T-S) diagram, and show how different sets of T-S values for different water masses can have identical    densities.

      44. Name, describe, and elaborate on the origin and activity of the three major deep-water masses.

45.   Describe and illustrate the classic model of pure thermohaline circulation.

      46.  What is the process of “caballing”?

     47.  What is the vast global-scale ocean circulation system current system termed the “global conveyor belt for heat transport”?

48.    What are the two traditional types of methods for measuring currents?

49.  Which type of current measuring method works best for each type of water mass?

50.  What is “acoustical tomography”, and what is its usefulness in studying ocean currents?


Essay Questions - A super effective means of “getting down” the science terms and concepts is to answer questions in essay form (usually require answers of about 10 sentences in length).  The following are key questions concerning the material covered for this midterm exam:  

1. Describe the Earths heat budget. It is not necessary to give a quantitative answer, but your answer should include a description of the major processes affecting the suns energy after it enters the Earths atmosphere. How will increasing carbon dioxide concentrations in the Earths atmosphere affect the Earths heat budget? Indicate the specific processes affected as well as the overall effect on the budget.

2.  Describe the changes in water density in the upper ocean layer over the annual cycles at tropical, temperate, and polar latitudes and the corresponding changes in water temperature. Indicate at which times of year, in each region, that the water column is unstable and mixing with underlying water occurs. Diagrams may make this easier.

   3  Describe the circulation of the Atlantic Ocean below 1000 m depth. Discuss the sites of formation of water masses, how they form (e.g., cooling at the ocean surface, mixing of other water masses), and their paths of flow. Include the following water masses in your answer: North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AAIW), Antarctic Bottom Water (AABW), and Mediterranean Water (MW).

4.    From 0° to 30° N latitude, the Northeast trade winds blow from the northeast; between 30° and 60° N latitude, the Westerlies blow from the southwest. Explain how this  wind pattern, in along with the Earths rotation (Coriolis effect), causes the clockwise flow of currents circling the North Pacific Ocean , the North Pacific Gyre.

5.  Define and discuss in adequate detail the vast global-scale ocean circulation system current system termed the “global conveyor belt for heat transport”.   Also discuss how it has primary importance in moderating and shaping Earth’s climate