EXPLAIN: 60-75 MINUTES
There are several variables that play a role in predicting the start of an El Niño. In simplest terms they include abnormally warm sea surface temperatures, SST of the tropical Pacific, weakening of the trade winds, and changes in rainfall variability over the Pacific region. Students will be looking at these variables to make predictions about the next El Nino, based on the evidence they analyze. Students will look at sea surface temperature anomalies, SST, and rainfall variability anomalies.
Looking at real data may be new for your students. New can sometime equate to frustration. Determine how best to work this section with your students in an effect to quell frustration yet positively impact learning. There is vocabulary that is important to understand, but will best be addressed within context.
Provide students with the information in the opening of the Explain section.
Students need to understand the word “anomaly”. Simply stated it is something that deviates or differs from normal or what is expected. Ask students to apply this definition to weather and climate. Have them write a working definition for weather and climate anomalies in their science notebook. Also let students know the anomalies they will be looking at are compared to a baseline average period from 1981 – 2010.
Table 1 – Oceanic Niño Index and El Niño Impact Map
Table 1 shows the last 64 years of El Niño and La Niña events. Students need to complete and answer the question below in their science notebook.
- Calculate the number of El Niño events, including all weak, moderate, and strong events over the past 64 years.
- Find what percent of these events are categorized weak, moderate, and strong.
- What types of weather events can the U.S. expect as the result of an El Niño event? Would the impact vary based on the intensity of the event? Explain.
- How could an El Niño event affect the economy, especially our goods and services?
Figure 1, Niño Regions and Sea Surface Temperature Anomaly Maps for January 2002, 2006, 2009, and 2014
- Does 2014 look more similar to a weak or moderate El Niño event year? Explain.
- Is this enough evidence to predict the strength of El Niño this year? Why?
- Why do you think the ability to predict significant weather events has improved over time?
Figure 1, Niño Regions and Precipitation Anomaly Maps for January, 2002, 2006, 2009, 2014
- How does 2014 compare to the 2009 El Niño event? Base your response on a closer analysis of Niño Region 4.
- Again taking a closer look at Niño Region 4 on all four maps, would you say that during these events this region is experiencing more or less rainfall? Explain how you came to that conclusion.
- Why do you think it is helpful or not helpful to have access to data from a lengthy period of time, i.e. decades, centuries, versus over just 3-5 years?