


Introduction to Physical Oceanography
Homework Set 5
Due 8 October 2008


  1. Ekman Pumping. Go to the NOAA Pacific Marine Environmental Laboratory Live Access to the National Virtual Ocean Data System. Click Select dataset: By Dataset Name. Click on the COADS Monthly Climatology. In the new window, select wind vectors and click Next > . In the new window, verify you are requesting a global plot of mid-January vector winds (the default), then select "North Atlantic" from the pull-down menu for Region. Click Next > . This will cause the NOAA server to open a pop-up window and download the map, so be sure your browser is configured to allow pop-up windows.
    1. Print the map.
    2. On the map, carefully sketch the Ekman transports driven by the winds in the North Atlantic.
    3. Where in the North Atlantic do you expect to find a dome of warm water produced by Ekman pumping which produces down welling in the center of the ocean dome?

  2. Upwelling.You are planning a spring-break vacation to the beach. You decide to go to the southern hemisphere for a change in pace. You also decide to go to a beach near 25°S because you know that the descending air of the Hadley circulation in the atmosphere leads to clear sunny skies at this latitude.
    1. Look at a map of mean sea surface temperature Click on Filled Contour and Global 50 km with Ice (or a Navy map-use climatology for 21 March) of the ocean at 30°S at the east and west coasts of the three southern-hemisphere continents. What are the values of temperature?
    2. What is the temperature difference between the east and west coast of each continent at this latitude?
    3. Describe at least two processes that might cause the difference in temperature? Hint: You may wish to use information in Fig. 4.2 to argue your case.
    4. Do you want to vacation at an East or West coast?

  3. Influence of the Ocean on Weather. Why does the east coast of the North America from 20°N to 35°N have much different weather than the west coast?
    1. Please list at least three processes that may contribute to the differences.

  4. Currents in Gulf of Mexico. Both the Mercator Project in France and the US Navy calculate surface geostrophic currents in the Gulf of Mexico by assimilating satellite altimeter data into numerical models of ocean circulation. Let's compare their calculations.
    1. Navy Model.
      1. Go to the Naval Research Laboratory Global Ocean Analysis and Modeling web page. Click on Atlantic Ocean. This brings up a new web page.
      2. Click on Gulf of Mexico.
      3. On new web page, click on Speed/currents Nowcast snapshot archive.
      4. On new web page, Click on Month date to get a map of currents.
      5. Print the map of Unclassified: 1/32° Global NLOM map of current vectors in the Gulf of Mexico.
    2. Mercator Model.
      1. Go to the Mercator Ocean web bulletins web page. Click on 1/15° North Atlantic and Mediterranean Expert Bulletin image. This brings up a new web page.
      2. Select bulletin date: same date as 4.a.iv above.
      3. On new page, click on Zonal maps.
      4. On new page, which shows map choices in the North Atlantic, click on F to bring up Gulf of Mexico map page.
      5. Click on Surface current image.
      6. Print pam: Initialized velocity: U on date near 3m.
    3. Compare the maps in the Gulf of Mexico in detail. How do they agreee, how do they differ?

  5. Currents. You are given a record of currents measured by a current meter at a depth of 10 meters in the central Gulf of Mexico from January 2004.
    1. What types of currents do you expect to find in the record? There are probably four types. Ocean engineers may want to add a fifth type.
    2. How can you tell one type from another? We have not discussed all different types of currents, so you may not know how to differentiate some types.

Revised on: 27 August, 2008

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