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PERIOD

Remember that one of our goals for this semester is to examine the earth as a system and the natural cycles that help sustain the planet and the life on it. One of these cycles is El Nino/La Nina. Scientists have learned how air/ocean interactions generate this cycle of events but do not know why it occurs and its contribution to maintaining the integrity of the planet. Today we begin our investigation of this phenomenon using computer visualizations to understand what are some of the major characteristics of the El Nina/La Nina cycle. In order to understand complex events we begin by collecting data, visualizing this information so that we can analyze and interpret it, and then generate computer models to help us understand the complex interactions that create these events.

Collecting Data: The source of our information comes from remote sensing. The U.S.-French TOPEX/POSEIDON satellite was launched on August 10. 1992. Itās mission is to provide data on ocean circulation to help scientists learn more about how the ocean affects climate change. It orbits the earth about 4,700 times each year covering 95 percent of the ice-free oceans every ten days.

Visualizing Data: You will be examining the same set of computer visualizations from March 25, 1997 through January 17, 1999 that scientists around the world have used to help understand El Nino/La Nina events that have a global impact. Your assignment is to explore these visualizations and determine how scientists understand the onset and weakening of El Nino followed by the onset and weakening of La Nina.

1. You will work in teams of four. Each team will have a poster of 21 computer visualizations and a scale that translates TOPEX-POSEIDON measurements into a color scheme.

2. Your team will examine the images in sets of three and focus on the areas and patterns of change since El Nino/La Nina are departures from "normal" conditions. Hold the color scale bar under the three images to identify the patterns of change. Slide the color scale bar under the next three images as you continue your exploration.

3. Use the information you learned from reading Davielleās article on the science of El Nino to help you interpret your findings.

Answer the following questions in complete sentences.

1. What geographic area is the focus of all these images? What features do you recognize that confirm this. (If you need help consult a map or globe in the room.)

2. Examine the color scale. What measurements do these colors represent?

3. How big is a millimeter? Does it amaze you that a satellite is capable of taking measurements this accurate?

4. What does a positive value mean?

5. What does a negative value mean?

6. Are positive values warmer or colder than normal?

7. Are negative values warmer or colder than normal?

Data Analysis

8. Make a chart that contains the following information for each 3 image block:

Beginning and ending date

Description of patterns of change

Geographic areas where change has occurred

Remember to hold the color scale bar below the visualizations to help you!

9. Scientists recognized the onset of El Nino in March 1997, identified its peak in January 1998 and predicted its weakening or dissipation in May 1998. Explain how your observations help to support or confirm these scientific conclusions.

10. How would you explain to a friend what happens during an El Nino cycle?

11. Use your observations to explain why we had such a wet winter in San Diego last year.

12. Scientists predicted the onset of a La Nina in August 1998, a definite La Nina pattern in November 1998 and its weakening in January 1999. Explain how your observations help to support or confirm these scientific conclusions.

13. How would you explain to a friend what happens during a La Nina cycle?

14. Use your observations to explain why we are having a drier than normal winter this year.

15. Explain why you think El Nino and La Nina events can effect weather every where on the planet.

16. What are the benefits of animating these images?

17. What patterns stand out because of the animation process?

18. Does changing the speed of the animation enable you to understand the patterns better?

19. Why is it important to have this type of scientific information available on the Internet?

20. Why are computer visualizations so important to the scientific process?

Remember that the next step is for scientists to generate computer models to help understand and predict future El Ninos and La Ninas to help us prepare for possible devastating effects. In a future activity you will compare some computer generated visualizations with the actual visualizations you studied today. This will help you to interpret how well these models can simulate events in the real world.