Upwelling and Downwelling

Name ______________________
Lab Grade ______/10
Date __________
Period _________
Lab # _____ - Upwelling and Downwelling
Background Information: Oceans are dynamic places where water moves due to changes in
temperature, density and salinity. Deeper water that moves to the surface is called
upwelling. When nutrient rich, deep water moves to the surface, biological productivity
increases. People rely on this upwelling to maintain marine populations for fishing. Surface
water that moves to greater depths is called downwelling. The net result is that heat,
dissolved materials and surface waters rich in dissolved oxygen move to greater depths.
Objective:
• Determine where and why upwelling and downwelling occur in the Atlantic and Pacific
Oceans
Materials: ESRT, Green, Blue, Red and Black color pencils
Time: 1-2 Periods
Procedure:
PART A - EKMAN TRANSPORT
1. Due to the Coriolis Effect, projectiles are deflected to the ____________ in the
Northern Hemisphere and to the _______________ in the Southern Hemisphere.
2. From the equator to the poles, the coriolis effect (strengthens, weakens)
3. Water is deflected to the _____________ of the prevailing wind in the Northern
Hemisphere and water is deflected to the ____________ of the prevailing wind in
the Southern Hemisphere.
4. At the equator there is (no measurable, a significant) Coriolis effect.
5. From the equator to the poles, the ocean water direction is (more, less) affected by
the Coriolis Effect.
6. At the equator, ocean water (is, is not) deflected.
7. The Swedish physicist named V. Walfrid Ekman (1874-1954) describes the movement
of water based on observations of a Norwegian explorer, Fridtjof Nansen.
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8. Ekman determined that ocean water is deflected 45° to the direction of the prevailing
wind in the Northern and Southern Hemispheres. Draw this angle and label it
“Surface Layer” in the diagram below. Also, Ekman determined that water is
transported at 90° from the prevailing wind direction in the Northern and Southern
Hemispheres. Draw this angle and label it “Net Water Movement”.
WIND
9. Open the ESRT to the Surface Ocean Currents. Color the continents GREEN.
10. Use a pencil to draw the following latitudes and label each latitude on the left side of
the page: 0°, 30° N and S, 60° N and S and 90° N and S.
PART B - NORTHERN HEMISPHERE
11. Open the ESRT to the Planetary Wind and Moisture Belts in the Troposphere.
Between what latitudes do the prevailing westerlies move? __________________
Use a RED color pencil to draw the prevailing westerlies on the map of Surface Ocean
Currents. Include as one of the arrows, a RED arrow over the Gulf Stream (Gulf
Stream Wind Arrow).
12. To illustrate the “Net Water Movement”, use a BLACK color pencil to draw an arrow
90° to the Gulf Stream Wind Arrow. Remember: Deflection is to the _______ in the
Northern Hemisphere.
13. According to the ESRT - Planetary Wind and Moisture Belts in the Troposphere,
between what latitudes do the trade winds move? _________________________
Use a BLUE color pencil to draw the trade winds on the map of Surface Ocean
Currents. Include as one of the arrows, a BLUE arrow over the North Equatorial
Current (N.E.C. Wind Arrow).
14. To illustrate the “Net Water Movement”, use a BLACK color pencil to draw an arrow
90° to the N.E. C. Wind Arrow. Remember: Deflection is to the _______ in the
Northern Hemisphere.
15. The two black arrows are pointing (toward, away from) each other at 30°N.
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16. There is a (mounding, depression) of ocean water at 30°N. Think of this as a hill that
water must move down but as it moves down the water is deflected to the (right,
left). This result in the (clockwise, counterclockwise) movement of gyres in the
Northern Hemisphere.
17. Ocean water moves (toward, away from) the East Coast of North America.
18. Water moves (up to the surface, to greater depths) to replace the moved surface
water.
19. (Upwelling, Downwelling) occurs along the East Coast of the USA.
PART C - SOUTHERN HEMISPHERE
20. Now lets focus our attention on the Southern Hemisphere. According to the ESRT -
Planetary Wind and Moisture Belts in the Troposphere, between what latitudes do the
southwesterlies move? _________________________ Use a BLUE color pencil to
draw the southwesterlies on the map of Surface Ocean Currents.
21. According to the ESRT - Planetary Wind and Moisture Belts in the Troposphere,
between what latitudes do the northeasterlies move? _______________________
Use a RED color pencil to draw the northeasterlies on the map of Surface Ocean
Currents.
22. Deflection is to the _________ in the Southern Hemisphere.
23. Use a BLACK color pencil to draw arrows that illustrate the 90° of the “Net Water
Movement” of the Brazil and Benguela Currents.
24. There is a (mounding, depression) of ocean water at 30°S. Think of this as a hill that
water must move down but as it moves down the water is deflected to the (right,
left). This result in the (clockwise, counterclockwise) movement of gyres in the
Southern Hemisphere.
25. Use a black pencil to draw the “Net Water Movement” along the Peru Current.
26. Ocean water moves (toward, away) from the East Coast of South America.
27. Water moves (up to the surface, to greater depths) to replace the moved surface
water.
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28. (Upwelling, Downwelling) occurs along the East Coast of South America.
29. According to the ESRT, the winds along the equator move from the (west to east, east
to west).
30. Warmer waters accumulate in the (western, eastern) Pacific Ocean.
31. More evaporation of ocean water occurs in the (western, eastern) Pacific Ocean.
32. Low pressure develops in the (western, eastern) Pacific Ocean.
33. There is more precipitation in the (western, eastern) Pacific Ocean.
34. The eastern Pacific Ocean is (wetter, drier) than the western Pacific Ocean.
35. Label the Western and Eastern Pacific Ocean as: high or low pressure and wet or dry.
Source: New York State, Earth Science Reference Tables 2001
36. During an El Nino episode, the high and low pressure of the Pacific weakens. The
east to west winds (strengthen, weaken).
37. The wind direction moves from the west to the ___________.
38. Warmer equatorial waters move from the _____________ to the ___________.
39. Water moves (toward, away from) the West coast of South America.
40. Water accumulates and sinks along the west coast of South America. This
(strengthens, weakens) upwelling along the West coast of South America.
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41. Nutrient levels (increase, decrease) along the West coast of South America.
42. Biological productivity (increase, decrease) along the West coast of South America.
43. During a La Nino episode, the normal high and low pressure systems of the Pacific
strengthen. The east to west winds (strengthen, weaken).
44. During a La Nina episode, the Peru Current (weakens, strengthens).
45. There is a net movement of ocean water (toward, away from) South America.
46. (Upwelling, Downwelling) occurs along the coast of South America.
Summary of Data:
Hemisphere Deflection
Latitude of
Ocean Water
Mounding
Gyre Direction
(Clockwise or
Counterclockwise)
Upwelling
(West or
East Coast)
Downwelling
(West or East
Coast)
Northern
Southern
47. For each diagram below, use the following terms with an arrow where appropriate: Net
transport, Downwelling, Upwelling
Southern
Hemisphere
48. Upwelling or Downwelling? ____________________________
49. Example of Coast __________________________________
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Northern
Hemisphere
50. Upwelling or Downwelling? ____________________________
51. Example of Coast ___________________________________
PART D - INTERNET RESOURCES
52. Now you will go to a website that discusses ocean currents. Go to
http://oceancurrents.rsmas.miami.edu/
53. Click on the Atlantic Ocean on the world map or click on “Atlantic Ocean Currents”.
Click on “Name/Location”.
54. Move your cursor over the Atlantic Ocean to find the following currents: Gulf
Stream, Brazil and Benguela.
55. At the top of the page click on “Pacific”. If the website has completed this part of
the web page, then locate the Peru Current.
56. Go to http://podaac-www.jpl.nasa.gov/ost/. Click on the image to enlarge it.
57. Next we will view a map that shows sea surface height above the mean sea surface in
______________.
58. What does red, orange and yellow represent on the map?
59. What is a positive sea surface height?
60. What does blue and purple represent on the map?
61. What is a negative sea surface height?
62. Approximately what is the highest sea surface height above the mean sea surface?
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63. Convert the mm value to cm. ________________
64. In the box below draw a line of the length in the question above.
65. Approximately what is the lowest sea surface height below the mean sea surface?
66. According to the image, sea levels are generally (high, low) in subtropical portions of
the ocean basins.
67. These locations have (mounds, depressions) of water as identified earlier in this
investigation. Note that factors in addition to Ekman transport affect the dynamic
topography of the ocean surface. One factor is water expansion due to increased
temperature as found in the western Tropical Pacific.
Conclusion: (Answer in complete sentences)
68. How does the occurrence of an El Nino affect ocean circulation and biological
productivity?
69. How does the occurrence of a La Nina affect ocean circulation and biological
productivity?
This laboratory investigation was modified from
DataStreme Ocean Benchmark Investigation 6A
Wind-Driven Ocean Circulation
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