Topic Guide: Winds and Surface Currents

 

In this activity you will form groups, conduct research into winds and surface currents, and report back to your lab section in the form of a presentation. At the end of this activity you will find suggestions for the format of the presentation. You will use the data you investigate as evidence for your statements. Please use these suggestions and the “How to make a class presentation” (Resource 1) as guidelines for your presentation.

 

Overview:

In preparation for this mini-study, you should be sure that you understand how the uneven heating of the Earth, from the Sun, and the Coriolis effect combine to produce the "ideal" global circulation pattern that consists of three circulation cells in the Northern hemisphere and three circulation cells in the Southern hemisphere. The wind pattern is similar, but differs from the ":ideal" pattern because of the continents and variations in the sea surface temperature from the ideal. You should also review the Eckman Spiral, which explains how winds drive the surface ocean currents. This will help explain not only the major ocean currents, but why upwelling occurs in some locations.

 

Key processes and concepts to review before beginning:

Resources:

 

After completing this investigation you should be able to:

  1. Describe differences between the simple “ideal” pattern and real atmospheric and oceanic circulation patterns
  2. Understand the roles wind patterns play in oceanic circulation
  3. Explain the relationship between atmospheric and oceanic circulation patterns and climate zones
     

You can go straight into exploring the data, but if you need more background information about winds and surface currents, please review the websites that provide background information (found after the data section).

 

Atmospheric Circulation Data:

This site shows an animation of the wind patterns for last five days!

http://haifung.jpl.nasa.gov/index.html

Don't miss the special attraction section.  You will definitely want to look at the animations. Be sure to check out the source information for the data. Below (Figure 1) is  a screen capture from one of the animations. You can control the speed and direction of the animation by sliding the control at the bottom of the screen from left to right.

 

 

Figure 1:  A screen capture from JPL's QuikScat Daily Wind Report Homepage.

 

• How do the circulation patterns in the animations differ from the ideal circulation patterns as shown in the textbook?

 

• Why are there regions in the Atlantic and Pacific Oceans called "Hurricane Alleys?"

 

The Cloud overlays are also very interesting. These are the latest wind data overlaid on Goes IR4 imagery. In these graphics the various colors of the arrows represent the wind speed, with blue the lowest and magenta the highest wind speed.

 

The following site shows wind speed, wave height, and water vapor data averaged over various time frames. The ten day averages are easiest to view because the satellite coverage is complete over the globe.

http://podaac.jpl.nasa.gov/topex/www/ql_index.html

In viewing these data, you should look at the archives of the 10 day averages. Ask yourself if there is a relationship between time of year, winds speed, wave height, and water vapor content of the atmosphere. Can you explain any of these observations with the idealized global circulation model in the textbook?

 

http://www-ccar.colorado.edu/~realtime/global-real-time_winds/

This website, served by the Colorado Center for Astrodynamics Research is home to the Global Near Real-Time Wind Speed Data Viewer. This site allows you to view maps of wind speeds for any region in the global ocean (60°S to 60°N latitude). When you are doing research on you specific Earth Summit country or if you are interested in a specific region, be sure to put in the proper latitude and longitude information.

 

Climatological Data:

Because the winds vary from day to day and year to year, it is often difficult to see the overall average pattern that persists in spite of these variations. To average out these variations, data must be averaged over many years. For example, the Hellerman-Rosenstein wind stress climatology dataset at the ferret Live Access Server averages wind for each of the 12 months over the years between 1870 and 1976. This dataset will show meridional (South to North) and zonal (West to East), and wind vectors (which are easiest to visualize because it shows the wind  direction as a vector). A positive value of zonal wind indicates flow from West to East and a a positive meridional value indicates flow from South to North. Other wind stress datasets show only the meridional and zonal plots, so you have to use both plots to determine the wind direction. The advantage of these other datasets is that they pertain to more recent data.

   

Alternate winds site:

http://ingrid.ldeo.columbia.edu/

The above link takes you to the IRI/LDEO climate data library. It’s a great resource! It contains powerful animations of the winds and precipitation on a global or regional basis. It will be a very powerful resource for finding weather and climate data on your Earth Summit country. The two links below are the same site, but take you to important locations on the site, for this study.

http://ingrid.ldeo.columbia.edu/maproom/

http://ingrid.ldeo.columbia.edu/maproom/.Regional/

 

Ocean Circulation Overview

The link below will provide you with some overview information. http://earth.usc.edu/~stott/Catalina/Oceans.html

You should be able to answer the following questions after reading this material.

  1. What is the driving force behind ocean currents?
  2. What is the Coriolis effect?
  3. How does the Coriolis effect work?
  4. Why is the direction of deflection caused by the Coriolis effect different in the Northern and Southern Hemispheres?
  5. What are the most important role of surface ocean currents?  

 

http://www.aoml.noaa.gov/phod/dac/dacdata.html

Look at several of the graphics formed by analyzing real life data from the Drifting Buoy Data Assembly Center. Be sure you understand what you are looking at. There are many choices for representing data and not all will be applicable to what you are interested in discovering about ocean circulation.

 

How do the real data compare to the idealized ocean surface circulation graphic from the previous web site or from your textbook?

 

The following link concentrates on the equatorial Pacific, for purposes of studying the El-Nino phenomenon.

http://www.esr.org/sfcurrents/sfc.html

Background information: Please take some time to learn more about the background information available for the topic of winds and surface currents. If you learn something new and interesting, please share it with the lab in your presentation.

 

Presentation Framework

Your presentation should include a brief overview explaining the significance of winds and surface currents. You should then choose as many of the following topics as is necessary to explain the concept. Choose topics that you think might be relevant to understanding winds and surface currents. Your presentation should include interesting findings from your investigations, backed up with data. You must use the physical data in your presentation.

 

You may choose from the following list of topics, or investigate a topic of your own. The topics in the list are examples of investigations that could be made using the data available at the URL’s listed above.

 

Data driven topics:  

Overview type topics:

 

<Oceanography Home><Index of Mini-Studies>