click here for a higher graphics version

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

Save and analyze three important mages 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.

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, occaisionally 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.

This has a number of several devestating effects and problems. For example:

Warm waters at the surface keep the cold nutrient-rich bottom waters from coming to the surface and all the fish leave the area. Bad for the fishermen, eh?
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.
The lack of warm water moving to the western Pacific causes droughts and forest fires in souteast Asia and Australia.
Hawaii and Tahiti experience rare cyclones and unusually severe tropical storms.

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 analyize 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

La Nina