Curry School of Education, University of Virginia
www.teacherlink.org/content/science/
The Impact of El Niño, Pt. 1
Grades 7-12
The most recent El Niño event (1997-98) was blamed for many weather disturbances,
including hot summers, changes in rainfall, and mild winters. Few people really
understand what El Niño is and whether
it actually affects the weather in their
own region.
In this activity, students will download
regional weather data available on the
Internet to an Excel spreadsheet to
calculate average temperature, then
graph the results. Students can then
analyze the graph to determine if El
Niño cycles have affected the weather
patterns in a selected geographic area.
This inquiry activity challenges students
to use their analytical skills and
creativity to make sense of the weather patterns they identify through the data.
NOTE: This activity uses a spreadsheet to answer a scientific question and assumes
understanding of the basic operation of a spreadsheet. Although it is an effective activity
for building upon and reinforcing basic spreadsheet skills, it is not a good activity for
introducing spreadsheets.
Scientists often use data sets that are too large to make sense of without some data
management tool. One common data management tool is a spreadsheet, which allows
scientists (and students) to summarize easily large data sets both statistically and
graphically.
In this activity students create and analyze graphs of historical weather data they
download from the Internet to develop conclusions about how El Niño has affected
temperatures and rainfall in the selected area.
Virginia Earth Science Standards of Learning addressed in this
activity include:
ES.1 The student will plan and conduct investigations in which:
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Technologies, including computers, are used to collect, analyze, and report data
and to demonstrate concepts and simulate experimental conditions;
Scales, diagrams, maps, charts, graphs, tables, and profiles are constructed and
interpreted
A scientific viewpoint is constructed and defended.
ES.2 The student will demonstrate scientific reasoning and logic by:
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Analyzing how science explains and predicts the interactions and dynamics of
complex Earth systems;
Recognizing that evidence is required to evaluate explanations;
ES.13 The student will investigate and understand that energy transfer between the sun,
Earth, and the Earth's atmosphere drives weather and climate on Earth. Key concepts
include:
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Prediction of weather patterns; and
Weather phenomena and the factors that affect climate.
Technology: Computer with Internet access and compatible spreadsheet program
(Microsoft Excel, Appleworks, etc.)
The procedure for downloading the data and creating the spreadsheet are probably more
difficult to describe than actually to do. You may want to download the actual Excel file
from our example to see what the spreadsheet is supposed to look like: SanDiego
Data.xls [not yet available]
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NOTE TO TEACHERS:
These procedures are written to show you how you might use these technologies to teach
science concepts. Suggested questions, approaches, and expected answers are all
provided. Therefore, these activity descriptions should be used as a guide for your
instructional planning, rather than as step-by-step directions for students.
Getting Started
What do you think El Niño is?
What areas of the world are most often affected by El Niño?
How does an El Niño event affect the climate in the United States?
Before you begin this activity, you can get a general understanding of these issues and the
El Niño phenomenon by accessing some of the websites listed in the Resources section.
Does El Niño affect the climate where you live?
How could you conduct your own study to determine if El Niño has affected your
climate?
In this activity you will use a spreadsheet and its graphing capabilities to compare the
weather patterns of the most recent El Niño years (1997-98) with historical weather
patterns in a specific region. You will need data on monthly temperature for each year of
the past several decades.
One good source of historic weather data is the NOAA Regional Climatic Center web
site.
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Some regional climate centers provide more easily accessible historic weather data than
others. You will find the Western Regional and Southern Regional Climate Centers have
the most easily accessible data for our purposes. Initially, you may want to choose a
location from one of these regions to explore.
The examples shown here will use San Diego, CA. To access the monthly temperature
data from the Western Regional Climate Center web page, go to Historical Climatic Data,
then Western U.S. Historical Summary (individual stations). From this screen, select So.
California, then select the San Diego WSO. Under "Period of Record," select Monthly
Temperature Listing (Average) under the heading "Temperature."
Download the Data to a Spreadsheet
(Note: The directions provided here are for Microsoft Excel, but other spreadsheet
programs should work similarly.)
You will need to copy and paste the data from the Web browser to your spreadsheet.
Highlight the data only (leaving out the text at the beginning of the page and the column
headings). Including any text that is not part of the actual data will confuse the
spreadsheet. Starting with the first year (1914 for San Diego) select and copy all the data
down to the last data record. Do not include the Period of Record Statistics.
Paste this data into your spreadsheet, leaving a couple of empty rows at the top for
column headers.
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[Alternate Method: You may save the data in a text file, then import it to the
spreadsheet. From the Web browser Select File, Save as to save the data as a text file.
Open this text file and delete all extraneous text at the beginning, as well as all the Period
of Record Statistics at the end. Close and save the text file. Open a new spreadsheet and
open the saved text file. Excel will provide a Data Import Wizard enabling you to format
the data in appropriate columnar form in a few easy steps.]
You may need to delete extraneous columns created in the process of pasting the text into
the spreadsheet. Also, some of the data may have letter symbols associated with them,
such as "68.55a" or "73.35z." These letters must be removed; otherwise, the spreadsheet
does not recognize these as numbers. To remove them, use the Find/Replace option
found under the Edit menu. Type in the extraneous letter in the find box and leave the
replace box empty. Then click the Replace All button. Do the same for any other letters
found in the data. You may need simply to retype the data in some of the cells.
You will also need to delete the entire "Annual" column of data, which is located after the
December column.
Remove years in which all the values are 0, because such rows usually represent years
when data were not kept, and they can skew the results of your analysis.
Keep in mind that cleaning up the data sets in this way is a normal part of the process
scientists have to go through before they can analyze large data sets.
Finally, add column headers, beginning with "Years" in the first column and the months
January through December in the remaining columns.
Calculate Average Temperature Data
How do you think the overall monthly temperature averages for your selected area
compare to the average temperatures during the 1997-98 El Niño event?
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If you tried to visually analyze all the data in your spreadsheet at once, interpretation
would be too difficult. One way to handle this problem is to calculate monthly averages
for the entire set of data. First create a new "Average" row under the last row of data.
Then for each month, in the new Average row you created, calculate the average as
follows: Type "=AVERAGE( )" with the cell range reference inside the parentheses; for
example, =AVERAGE(B4:B89)
As you look down the rows of data for each month, you can see that the temperature
varies from year to year. Comparing data from El Niño years to "average" temperatures
would not reflect that variability. Instead, we need a way compare the data to what are the
normal, or typical, temperature ranges.
Calculating the standard deviation allows you to take into account these ranges in
temperature each month, assuming the data are normally distributed, as is often the case
with temperature data. You can use the standard deviation function of the spreadsheet to
express the variability of the average monthly temperatures you determined earlier.
Create three more rows under the Average row: one to calculate the Standard Deviation
[=STDEV(insert cell range)] for each column, one for Average +1 standard deviation
(add the Average and the Standard Deviation cells for each column), and a third row to
calculate the average -1 standard deviation (subtract the Standard Deviation cell from the
Average cell for each column).
By definition, approximately 68% of the data from the temperature table will fall between
+1 and -1 standard deviation of the average. You can use this range as an indication of
typical temperatures for the month.
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Graph the Data
Now you are ready to compare temperatures during the El Niño event in 1997-98 to the
normal temperature ranges for your selected area. First you need to select all the rows
you are going to graph. Hold down the Control (Win) key or the Command (Mac) key,
while selecting each of the following rows with the mouse: (a) month labels, (b) 1997, (c)
1998, (d) Average + 1 Standard Deviation, and (e) Average -1 Standard Deviation.
Next, select the Chart Wizard button (or choose chart on the Insert Menu), and the Chart
Wizard box will appear. Select the line graph with markers displayed at each data value.
Follow the directions on the Chart Wizard to create your graph. The data from each row
you selected should be plotted, using the Month label row for labeling the x-axis.
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As you study the graph, look for areas where either of the El Niño year lines extend
beyond either the average +1 or average -1 Standard Deviation boundaries. Where the El
Niño year line falls outside the one Standard Deviation boundaries, you can say that the
El Niño temperatures for that month were warmer (or colder) than normal for the selected
region.
Was there any change in weather pattern during El Niño years?
From analyzing your graph, do you think the El Niño event affected temperatures in your
selected region?
Explain your reasoning.
(NOTE: You may want to discuss with students the concept that the decision to use ±1
Standard Deviation as your typical temperature range is a value judgment — not a hard
and fast rule. This realization can lead to an interesting discussion on tentativeness,
subjectivity, and other aspects of the nature of science.)
An expansion of this activity that explores El Niño's effects on precipitation may be
found at The Impact of El Niño Pt. 2.
Draw Your Conclusions
What do you think now?
Did the El Niño event of 1997-98 affect your area?
Be sure to support your conclusions with data presented in your graphs. You may find
that one, both, or none of the factors (temperature or precipitation) was affected during
this climatic anomaly.
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In addition to completing the graphs, have students write a paragraph to justify
whether the El Niño event of 1997-1998 affected the geographic area studied in
this activity.
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Provide students with a copy of a graphs showing temperature and precipitation
data from the El Niño event of 1986-87. Ask students to draw conclusions from
the data and write a paragraph to explain their findings, using the data in the
graphs to support their ideas.
For a more detailed explanation of this activity, see Bell, R. L., Niess, M. L., & Bell, L.
L. (2001). El Niño did it: Using technology to assess and predict climate trends. Learning
and Leading With Technology, 29, 18-26.
The following websites include background information on the El Niño weather
phenomenon:
El Niño: Online Meteorology Guide
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/eln/home.rxml/
This site an online teaching module from the University of Illinois including information
and animated graphics to explain an el Niño.
What Is an El Niño?
http://www.pmel.noaa.gov/tao/elnino/el-nino-story.html
This site, designed by the National Oceanic and Atmospheric Administration (NOAA),
provides more detailed explanations and animated graphics to explain an el Niño and
includes additional links for further information.
The Space Place: Whip Up Some El Niño pudding!
http://spaceplace.jpl.nasa.gov/topex_make1.htm
This NASA site is written for kids with simplified explanations. A movie is included to
show the progression of the December 1996 to June of 1998 taken from space. Additional
links are included on the site along with a recipe for El Niño pudding. This is a good site
for middle level (grades 5-8) students.
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The following are articles that may be used as background for claims made in the popular
media about El Niño:
Eastern United States
1. Crittenden, J. (2000, November 5). 'La Nada' blows in for winter - New nickname
for pattern may forecast more snow. The Boston Herald, p. 3. Retrieved May 27,
2002, from Lexis-Nexis Academic Universe database.
2. Associated Press. (1998, November 29). Warm El Nino Lurks in Sea, Along With
Its Cold Twin. The New York Times, Section 1, p. 40. Retrieved May 27, 2002,
from Lexis-Nexis Academic Universe database.
Central United States
1. Nicholson, B. (2001, August 10). Weather patterns bad news for state. The
Bismarck Tribune, p. A9. Retrieved May 27, 2002, from Lexis-Nexis Academic
Universe database.
2. Mitchell, S. D. (2002, January, 15). El Nino could mean another mild winter. The
Associated Press State & Local Wire, State and Regional. Retrieved May 27,
2002, from Lexis-Nexis Academic Universe database.
3. Johnson, G. (2000, February 4). Recent data suggest that our winters will be
getting a lot colder. St. Louis Post-Dispatch, p. A14. Retrieved May 27, 2002,
from Lexis-Nexis Academic Universe database.
Western United States
1. Schoch, D. (2001, April 5). California and the west; climate change linked to
decline in amphibians. Los Angeles Times, Metro Desk, p. 3, Home Edition.
Retrieved May 27, 2002, from Lexis-Nexis Academic Universe database.
2. Krehbiel, R. (2001, January 7). December weather one for the books. Tulsa
World. Retrieved May 27, 2002, from Lexis-Nexis Academic Universe database.
Contact:
Randy L. Bell
Asst Professor of Science Education
Curry School of Education
University of Virginia
Charlottesville, VA 22904
email: [email protected]
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