Comparing the Effects of El Nino and La Nina

Sea surface temperature warming during El Nino

Image courtesy Live Access Server

To compare the effects of El Nino and La Nina at two different longitudinal locations, but at the same latitude, using sea surface temperature and precipitation from real satellite data
Grade Level: 7 – 8
Estimated Time for Completing Activity: Two 50 minute class periods
Learning Outcomes:
  • Students will be able to obtain real sea surface temperature and precipitation data from satellite.
  • Students will be able to create maps and line graphs of data.
  • Students will be able to make comparisons and conclusions regarding the effects of El Nino and La Nina.
  • An Overview of El Nino and La Nina
  • Familiarity with latitude and longitude coordinates
  • Familiarity with Microsoft Excel
  • Computer with Internet Access
  • Map of the United States showing latitude and longitude lines
  • Colored pencils
  • Microsoft Excel or other spreadsheet software
AP Environmental Science Topics
Lesson Links:

The El Nino-Southern Oscillation (ENSO) is a global coupled ocean-atmosphere phenomenon. El Nino and La Nina are important temperature fluctuations in surface waters of the tropical Pacific Ocean. ENSO is associated with floods, droughts and other disturbances in a range of locations around the world. ENSO is the most prominent known source of interannual variability in weather and climate around the world. ENSO conditions seem to have occurred at two to seven year intervals for the past three hundred years. The mechanisms which might cause an ENSO are still being investigated. As the phenomenon is located near the Equator, it may affect both hemispheres.

The first signs of ENSO are:
1. A rise in air pressure over the Indian Ocean, Indonesia and Australia.
2. A fall in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean.
3. Trade Winds in the South Pacific weaken or head east.
4. Warm air rises near Peru, causing rain in the Peruvian deserts.
5. Warm water spreads from the West Pacific and the Indian Ocean to the East Pacific and it takes the rain with it, causing extensive drought in the Western Pacific and rainfall in the normally dry Eastern Pacific.

La Nina is the name of the cold phase of ENSO, during which the cold pool in the eastern Pacific intensifies and the trade winds strengthen. La Nina causes the opposite effects of El Nino. For example, El Nino would cause a wet period in the midwestern United States, while La Nina would cause a dry period.


Part I: Compare the effects of ENSO in two different locations in the United States. Latitude: 37 degrees North, and Longitudes: 116 degrees West (California) and 99 degrees West (Kansas).

1. Obtain a U.S. map, locate and plot the latitudes and longitudes of the two selected sites (Porterville, CA, and Hays, KS).
2. Predict similarities and differences in weather patterns over the past ten years of these two areas.
3. Make a side-by-side comparison line plot of precipitation using the Live Access Server (Advanced). Click the lesson link above for the Live Access Server.
4. Select Atmosphere, Precipitation, then click the Monthly Precipitation (GPCP).
5. On the menu to the left under ‘Line Plots’ select Time Series.
6. Click the Compare tab on the above menu.
7. Under the world map at the bottom of each of the four, enter the latitude and longitude values for your locations selected in step 1. You will only be using the top two maps since you are only comparing two locations. Note, for a single location your latitude value will be the same value in both the north and south location. Your Longitude values will be duplicated in the east and west boxes. This is because you are looking at single point on the map and not a large area.
8. Enter your range, Nov 1997 and Feb 1999, under ‘Plot Axis’ to the left of the four plots.
9. Click ‘Update Plots’ At the top left of your screen in the menu bar.
10. Should your line plots not appear you might have to go back and re-select ‘Time’ from the line plot options menu to the left for the changes to show up on the screen

Part II: Make maps of sea surface temperature in the Pacific Ocean during El Nino and La Nina phases.

1. To create sea surface temperature comparison maps, return to the Live Access Server, Select Oceans, check Daily Sea Surface Temperature (GHRSST), select Compare from the top menu.
2. Select Equatorial Pacific from the menu button denoted with a double downward arrow above the world map to the left of the screen.
3. Enter dates: November 15, 1997, and February 15, 1999 on separate maps. Click ‘Update Plots’ in the menu at the top.
4. Analyze the maps.

Part III (Optional): To create a data table and graph of precipitation comparisons in Excel, follow these directions:

1. Select Live Access Server (Advanced)
2. Select Atmosphere, Precipitation, Monthly Precipitation (GPCP).
3. Be sure to select ‘Time Series’ from the Line Plots drop down menu to the left.
4. Enter in your coordinates in the compass rose and then ‘Update Plot’ from the top menu.
4. To save as an ASCII file to analyze in Excel, Click on the ‘Save As’ button at the top of the screen. From the drop down menu under ‘select Format’ choose ASCII and make sure that your date range is what you want.
5. Save data table to desktop to import into Excel.
6. Repeat steps 3 – 5 for the second site.

Excel Directions:

1. Open Excel and select Import or Get External Data under the Data menu. Click on Import Text File.
2. Use the Browse window to select the precipitation file on your desktop or other file location.
3. A Text Import Wizard window should appear. On Step 1, Select Delimited. Be sure to Start Import at headings row. Click next. On step 2, select space delimited and finish. The data should now be neatly organized in the spreadsheet.
4. Delete all columns except date and precipitation amounts.
5. Highlight the two columns labeled dates and precipitation
6. Click the Insert on the menu bar, and Select Chart.
7. With the Chart Wizard open, choose the xy scatterplot with connecting line (no markers which is the bottom right choice) Click next.
8. Type a chart title and label the axis.
9. Generate the graph by selecting Finish. Place in worksheet by clicking OK.
10. Repeat for the second data file and graph.


1. Analyze the sea surface temperature maps. Which one is the El Nino phase and which one is the La Nina phase?

2. Write a paragraph comparing and contrasting the sea surface temperature maps.

3. Analyze the line graph showing precipitation comparisons. Which line is California? Which line is Kansas?

4. Compare and contrast both sites and write a paragraph on your observations. Relate the observations to the ENSO phases.

5. In which location would you rather live based on the precipitation amounts? Why?


1. How do you think any future climate change will affect the El Nino and La Nina phenomenon?

2. What information would you need to make this prediction?

3. How do you think this will affect the two comparison sites?

4. A more recent set of dates for this phenomenon is November 2009 and February 2010. Use this set of dates in place of the November 1997 and February 1999 that you used above to compete the procedure the first time through. Make a comparison between the two date ranges. What conclusions can you draw when comparing the two sets?

Lesson plan contributed by Marti Phipps, California, and Kathy Rome, Kansas

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