Oceanography Homework #4

(E4) Exercise #4: Exploring Coastal Upwelling 

Goals 

• Understand how scientists report direction in compass points, azimuth bearings, and quadrant bearings. 

• Investigate the relationship between winds, surface currents, sea surface temperature and upwelling and 

downwelling.

• Determine if upwelling or downwelling was occuring along the Pacific Northwest coast in September of 2013. 

Background 

Seasonal upwelling is a very important process not just to the Pacific Northwest but to many coastal regions in the world. During the summer in the Northern Hemisphere, upwelling is driven by winds blowing from the North to the South (Northerlies) that, combined with the Coriolis Effect, push surface water off-shore and out to sea. 

Upwelling pulls deep ocean water up to the surface making the surface coastal ocean more salty, cold, and nutrient rich. The added nutrients in the sunny surface waters trigger fast phytoplankton growth and reproduction, which is the base of the food web and supports the important fisheries along the West Coast of the US. 

Background Knowledge 

To measure and report relative directions on Earth, scientists use compass points, azimuth bearings, and quadrant bearings. This measurement system measures horizontal directions, as if you were in the air looking down at a flat surface. Take a few minutes to review these resources on compass points, azimuth bearings, and quadrant bearings: 

• Thinking in Circles (http://academic.brooklyn.cuny.edu/geology/leveson/core/linksa/comp.html). 

• Section: Points of a Compass (http://gwydir.demon.co.uk/jo/units/angles.htm#compass) 

The figure below summarizes these three systems by giving the location of the red star using each system. 

Compass point: SE Azimuth Bearing: 140° Bearing: S40°E

(E4) Exercise #4 – Page 1 of 10 

Once you understand the difference between the three systems (compass points, azimuth bearings, and quandrant 

bearings), complete the exercise below. 

On the drawing of a compass to the right, assume that “A” is zero degrees. List the compass point, azimuth bearing, and quandrant bearing of letters V, W, X, Y, and Z. 

W 

A

Y 

X 

Compass Azimuth Quandrant Point Bearing Bearing 

V 

______________ ______________ ______________ Z 

1) V.

2) W.

3) X.

4) Y.

5) Z. ______________ ______________ ______________ 

______________ ______________ ______________ ______________ ______________ ______________ ______________ ______________ ______________ 

If you think you understand compass directions, you may go on to the next part of this exercise 

The Exercise 

Our overall goal for this exercise is to answer the question: In late September 2013, was upwelling occurring on the Pacific Northwest coast? 

We will review indicators of upwelling using data from NOAA. We will then synthesize those indicators to decide if upwelling is occurring. Questions that you will answer in Tests & Surveys for this exercise are numbered below and indicated in bold, italicized text below. 

Columbia River 

Stonewall Bank Port St Georges 

California 

We will review several data sources for this exercise. We will review data from September 2013 for three NOAA buoy stations: Stonewall Bank, Port St Georges, and the Columbia River Bar. The approximate location of these buoys is highlighted on the map to the right. For your convenience, the buoy data you will use is included at the end of this exercise. You do not have to visit the links above for this exercise, unless you are interested in seeing the data sources. 

Washington 

Oregon 

We will also review maps of ocean current direction off the coast of Oregon. The data you will review is from this site: Surface Currents Of The Oregon Coastal Ocean. For your convenience, the map you will use is included at the end of this exercise. You do not have to visit the links above for this exercise, unless you are interested in seeing the data sources. 

NORTH 

(E4) Exercise #4 – Page 2 of 10 

Indicator #1: Wind Direction 

As we learned in our text readings, wind direction is an important driver of oceanic upwelling. Please review this concept on page 211, figure 7.12, of your textbook. 

6) What wind direction, relative to the shoreline, is favorable for upwelling along the west coast of North America? 

1. Towards the coast 

2. Away from the coast 

3. Parallel to the coast and blowing north 

4. Parallel to the coast and blowing south 

7) Given your answer to the previous question, what direction is this in azimuth degrees on a compass? 

a. 0°

b. 90° c. 180° d. 270° 

The three graphs on pages 7 through 9 of this worksheet show wind direction over five days for our three locations. The star in the upper left corner of each map corresponds to the stars on the map on the previous page. [Green: Columbia River, Blue: Stonewall Bank, Red: Port St Georges.] Larger versions of these graphs are also linked on the Exercise #4 page of Module (7) in Canvas. Take a few minutes to orient yourself with the data shown on each graph. 

8) What variable is displayed on the x-axis (horizontal, along the bottom) of each graph? ___________________ 9) What variable is displayed on the y-axis (vertical, along the left side) of each graph? ______________________ 10)What does the blue line of each graph represent? ___________________________________________________________________ 

Using the graphs of wind direction for each location on pages 7-9 of this worksheet, please answer the following questions: 

11)What is the average wind direction, in degrees, for each location? To determine the average, ignore any major fluctuations such as those on 9/21 and 9/24, and record the value that is most common on the graph. 

1. Columbia River Average Wind Direction______________ 

2. Stonewall Bank Average Wind Direction______________ 

c. Port St. Georges Average Wind Direction _____________ 

1. Columbia River Average Wind Direction______________ 

2. Stonewall Bank Average Wind Direction______________ 

c. Port St. Georges Average Wind Direction _____________ 

12)Referring to a compass, such as this one, convert the degrees above to a compass point (letters). 

13)Does the prevailing average wind direction at these locations indicate that upwelling may be occurring? Why or why not?______________________________________________________________________________________________ 

________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________ 

(E4) Exercise #4 – Page 3 of 10 

Indicator #2: Surface Currents 

Surface currents, driven by winds and Ekman Transport, drive upwelling and downwelling. Please review this concept on page 211, figure 7.12, of your textbook and answer the following questions. 

14)In areas of upwelling, surface currents move __________________ the coast. a. Away from 

b. Towards 

The image on page 10 of this worksheet shows the direction and speed of surface currents along the Pacific Northwest. On the map, the color of the triangles indicates speed and the arrows indicate direction. A larger version of this image is on page X of this exercise. A larger versions of this map is also linked on the Exercise #4 page of Module (7) in Canvas. 

c. Parallel to (along) 

15)What variable is displayed on the x-axis (horizontal, along the bottom) of the image? _____________________ 16)What variable is displayed on the y-axis (vertical, along the left side) of the image? ________________________ 17)What do the arrows represent on this image?________________________________________________________________________ 18)What do the colors represent on this image? _________________________________________________________________________ 

Look at the prevailing pattern of surface currents on this map to answer the question below. 

19)The data in the image of surface currents indicates that, overall, surface water is moving ____________________ the Pacific Northwest Coast. 

a. Towards b. Away from 

20)Do the surface currents at these locations indicate that upwelling may be occurring? Why or why not? 

____________________________________________________________________________________________________________________________________ ____________________________________________________________________________________________________________________________________ ____________________________________________________________________________________________________________________________________ 

(E4) Exercise #4 – Page 4 of 10 

Indicator #3: Water Temperature 

During upwelling, the water temperature along a coastline will change as ocean water is brought to the surface. Review section 7.3 in your text, and answer this question: 

21)Upwelling is associated with _______________ water brought to the ocean’s surface. a. Cold 

b. Warm 

1. 22)  The ocean temperature directly along the northwest Pacific Coast is _____________________ than that of the surrounding Pacific Ocean. 

   a. Warmer 

   b. Colder 

2. 23)  Does the water temperature along the northwest Pacific Coast indicate that upwelling may be 

   occurring? Why or why not? __________________________________________________________________________________________ ______________________________________________________________________________________________________________________________ 

The map below is similar to one that you reviewed in Exercise 3. This map is showing water temperature, at the sea surface, for September 22, 2013. Look at the image, and then answer the question beneath the image. 

(E4) Exercise #4 – Page 5 of 10 

Putting it all together 

We have now examined winds, surface currents, and ocean temperature for the Northwest Pacific Coast. Based on these three indicators, please answer the following question: 

24) In late September 2013, was upwelling occurring on the Pacific Northwest coast? Why or why not? Compose your answer in 5-10 complete sentences that summarize the three indicators you reviewed above. Use your own words, no quotes and no copying and pasting from the neither text nor online sources. 

Submitting your answers 

You will submit your answers to this exercise in a Quiz called (E4) Exercise #4 Quiz. Here are a few details on the quiz: 

• You will have 60 minutes to complete the quiz from the time you open it. COMPLETE THE EXERCISE QUESTIONS BEFORE OPENING THE QUIZ! 

• The password for this quiz is upwell 

• Work through the quiz by answering the questions with a paragraph response. You will be answering all of the 

questions in the Quizzes tool.

o Questions will be presented as a combination of multiple-choice and short answer questions. o For short answer questions, use complete sentences and your own words. 

Your instructor will manually grade parts of this quiz. You may not see a score immediately. Once your instructor finishes grading this exercise you will receive an announcement advising you that feedback is available. 

(E4) Exercise #4 – Page 6 of 10 

Wind Direction, September 20-25, 2013, Columbia River. 

(E4) Exercise #4 – Page 7 of 10 

Wind Direction, September 20-25, 2013, Stonewall Bank 

(E4) Exercise #4 – Page 8 of 10 

Wind Direction, September 20-25, 2013, Port St. Georges 

(E4) Exercise #4 – Page 9 of 10