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Searching for El-Nino

Overview

In this lesson, students observe monthly mean sea surface temperatures (sst) and wind speeds for years that include El-Nino phenomena and years that do not. Students then compare current observations with past years to predict the current status of the El Nino.

Exploration

Below you will find three large images from the National Oceanic and Atmospheric Administration (NOAA). The first image shows data for January 1991, the second image shows data for January, 1992, and the last image shows data for today.


January 1991

January 1992
Current El Nino Watch

What are the principle differences difference between January 1991 and January 1992? Consider first the mean values and then the anomalous values.

Which of the first two graphs does today's graph look most like? What parts are similar? What might this mean?

The January 1992 graph represents a phenomena called El Nino. In this lesson you will be studying the El Nino event , the global consequences, and analyzing the possibility of an upcoming El Nino.

Concept Introduction
 
 

Normally, winds blow to the west along the equator. This pushes warm waters to the west pacific and allows cold deep water, nutrient rich water to rise to the surface on the west coast of Central America. These nutrient rich waters are great for fishing. However, occasionally around late December, these strong westerly winds diminish and warm water stays near Central America. 

Why is it called an El Nino?

The term "El Nino" is derived from the Spanish term for "the Christ Child" or "little boy". It was first used by fishermen in Ecuador and Peru to refer to a warm ocean current that arrives on their shores around Christmas time. These episodes can last for several months, resulting in a reduction of nutrients and a corresponding reduction in the fish population. Sometimes, this warm water condition can persist well into May or even June, resulting in a less than abundant year for the fishermen.  But El-Nino affects more than just the local fishing economy off the western South American coast. 

For example:

 El Nino Schematic

 
South American Flood
  • Warm waters at the surface keep the cold nutrient rich bottom waters from coming to the surface and all the fish leave the area. 
  • These stationary warm waters encourage abnormally high evaporation and cloud development. These storms dump much of their precipitation on the United States in the form of floods and blizzards. 

    •  
    scorched forest
  • The lack of warm water moving to the western Pacific causes droughts and forest fires in southeast Asia and Australia.
  • Hawaii and Tahiti experience rare cyclones and unusually severe tropical storms.
  • Droughts occur in the southern part of the continent of Africa, leading to malnutrition and starvation.
    		•

    INVESTIGATION: Observe the NOAA JAVA Wind Machine. Although it takes a while to load, it demonstrates how winds and temperatures change over time. When you understand the characteristics of an El Nino, you can predict them!!

    Concept Application

    Now it is time to reflect on today's environment and analyze the possibility of a developing or subsiding El Nino.

    Sources of Current Data

    A look at the 1982-83 El-Nino event
    El-Nino Theme Page - from NOAA Pacific Marine Environmental Laboratory
    Equatorial Pacific SST
    NOAA El-Nino theme page
    The 1997-98 El-Nino/Southern Oscillation - Lots of reports from around the globe
    ENSO Home page - from NOAA Office of Global Programs
    El-Nino Update
    El-Nino.com - source of history, etc.
    El-Nino Advisory
    University of Washington's El-Nino Links
    University of Winnipeg's El-Nino Links

    Extensions