World Ocean Currents

Students will:

1. 
   Identify and describe Earth’s major ocean currents
   
2. 
   Interpret the relationship between prevailing winds and ocean currents.
   
3. 
   Identify the main characteristics of the world’s oceans including their size and the relationship between temperature and depth.
   
4. 
   Observe patterns in temperature data.
   
5. 
   Infer relationships between sea temperatures and phytoplankton concentration.
   
6. 
   Compare and interpret imagery depicting the Atlantic Ocean.
   

Today, oceanographers rely on a vast array of instruments and satellites to gather information about the speed, direction, and temperature of ocean currents. Maps of surface ocean currents, such as the one on page 532 of your textbook, are essentially summaries of the vast quantities of data collected from oceans all over the world.

1. 
   Using the Global Ocean Currents map on page 532 of your textbook, locate each of the ocean currents listed in Table 1. Use the map to complete the data table.
   
2. 
   Answer the analysis and conclusion questions listed after the table.
   

1. 
   Based on the data table, what is the relationship between the temperature of an ocean current and the direction of current flow relative to the equator? Explain why this relationship exists.
   

2. 
   What is the general relationship between a current’s temperature and the side of the ocean on which that current flows?
   

3. 
   Along the east coast of a continent, what is the general relationship between a current’s temperature and the direction of its flow? What is the general relationship along the west coast of a continent?
   

4. 
   In what direction, clockwise or counterclockwise, do the major circulation patterns rotate in the Northern and Southern Hemispheres? Why does each hemisphere have a different pattern?
   

5. 
   An ocean fog will occur when moist air blowing from a warm ocean current meets warm air over a cold ocean current. Which Australian coast (N, S, E, or W) is most likely to experience such fogs? Explain your reasoning.
   

1. 
   Use your textbook (p. 532) and the blank map of the world to draw and label all of the major ocean currents (from your data table). Use a BLUE colored pencil to draw the cold currents and a RED colored pencil for the warm currents.
   
2. 
   Using the data from Table 2, create (in Microsoft Excel) a bar graph that shows the surface area for the world’s three main oceans. Label the X-axis “Ocean” and the Y-axis “Millions of Kilometers.”
   

3. 
   Use the data from Table 3 to create (in Excel) a line graph that shows the relationship between the temperature and depth within the ocean near the tropics. Label the X-axis “Temperature (degrees C)” and the Y-axis “Depth (meters).”
   

Analysis and Conclusions

1. 
   Which ocean currents bring cool, nutrient-rich water from the poles toward the equator?
   

2. 
   Which ocean currents distribute warm water from the equator?
   

3. 
   Calculate the percentage that each of the three major oceans occupy out of total ocean area on Earth.
   

4. 
   The atmospheric pressure directly above the ocean surface is approximately 14.7 pounds per square inch, and for every 33 feet of depth, the pressure increases another 14.7 pounds per square inch. Knowing this, calculate the pressure for the average depth of the world’s oceans (12,171 feet). Show your work.
   

5. 
   List the world’s oceans from largest to smallest.
   

6. 
   Define the term thermocline. At what depths does it occur within the tropical oceans? (You may need to use your textbook for this one, or a simple web search)
   

1. 
   Log on to the Exploring Earth website, and access investigation ES2403.
   

You will examine differences in winter temperatures for cities at the same latitude and identify a pattern: coastal northern Europe has warmer winter temperatures than Canada or inland Europe. You will explore images of sea surface temperatures (SST) in the Atlantic Ocean and relate the warm waters of the Gulf Stream to the pattern of winter temperatures you observed. You will view animations showing the formation of warm and cold eddies in the Gulf Stream and identify each type in SST images. Finally, you will explore the connection between colder sea surface temperatures and the abundance of phytoplankton; you will infer that cold eddies in the Gulf Stream can be productive fishing grounds.

1. 
   About how wide is the Gulf Stream? How fast does it flow?
   

2. 
   What current does the Gulf Stream join with, and to which countries does it ultimately travel?
   

1. 
   Does it surprise you that palm trees could be growing in winter in Cork, Ireland? Why or why not?
   

1. 
   Record sea surface temperatures for January and July in Table 4 below.
   

2. 
   What patterns do you observe?
   

1. 
   Explain the effect of the Gulf Stream on the climate of coastal northern European cities.
   

1. 
   What are six factors that contribute to fishing conditions?
   

1. 
   What is an eddy?
   

2. 
   What do eddies consist of?
   

3. 
   What is the usual diameter of an eddy on the surface?
   

4. 
   How deep can eddies reach below the surface?
   

5. 
   The warm water eddy that formed at approximately 40N, 65W resulted from the interaction between which two currents?
   

1. 
   Where are the two warm core eddies located in relation to the main Gulf Stream current?
   

2. 
   What is the water temperature within the eddies? What is the temperature of the surrounding water?
   

1. 
   What is chlorophyll?
   

2. 
   What would result from there being higher concentrations of chlorophyll in an ocean area?
   

1. 
   In what temperature of water is phytoplankton generally more abundant?
   

2. 
   Based on the map of phytoplankton concentration, determine which areas of the North American coast would be best for the fishing industry.
   

1. 
   Locate Gulf Stream eddies on this map. Are these warm or cold eddies? Briefly describe their location.
   

2. 
   Describe the concentration of phytoplankton within these eddies. What can you infer about the abundance of fish in them?