El Niño and Ocean/Climate Conditions

Before doing this exercise, review the El Niño discussion, p. 202. Then visit the website www.ssmi.com/ssmiMonthly.html

Satellite images are one of the principal ways scientists map and monitor environmental conditions worldwide. This exercise uses satellite data gathered by the U.S. government for a variety of environmental monitoring purposes. This website is one of many excellent sources providing up-to-date environmental data. The monthly "static data" website provides graphic images of satellite data. If you are using a slow server, you may want to save a few of the images on your computer for answering the questions that follow.

For the questions below you will mostly be looking at atmospheric water vapor, or humidity. Keep this in mind: humidity is higher where evaporation is high. So high humidity indicates warm water; low humidity indicates cooler water.

The SSMI monthly data page lets you select a month and year to view, and provides four types of atmospheric information.

1. What are the four types of information shown? What units are used to measure these data types? (How fast is 1 wind-speed unit compared to how fast you walk?)

2. Look at the Atmospheric Water Vapor map for the current month. Bright red and yellow colors indicate high humidity in the air—and high temperatures. Where is the greatest concentration of red and yellow?

3. Look at November 1998. Then change to November 1997. (Each time you change years or months, you must click on the "Update Display" button to redraw.) Sketch on a piece of paper the general location of the red concentration in the Indian and Pacific Oceans in 1998 and in 1997. How do the two years differ?

4. Now look at the surface wind-speed maps for 1998 and 1997. Which year has the lowest wind speeds in the Pacific Ocean? In the Indian Ocean? Can you think of how wind speeds and ocean temperatures might be related?

5. Go backward, year by year, to see how the concentration of red changes over the years. For each year, mark an X on the graph below to show the approximate location of the biggest red concentration in the Pacific Ocean. During which years does the region of strong red/yellow expand farthest eastward?

6. If you have a fast network connection, start with January 1997 (or an earlier year) and hit the "next month" button to watch conditions change through the years. During which months do the 1998 El Niño conditions really start to develop?