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Activity 4
El Niño and Ocean Circulation
Think About It
Page F37
 What are some ways
of learning about the
distance to the water
surface, the depth of
the water, and the
water temperatures,
without actually touching
the water?
Date
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Activity 4
El Niño and Ocean Circulation
Investigate Part A
Pages F38-41
1a. What is the primary
difference between the
two data sets?
1b. How would you
communicate this
difference?
1c. Why is it important
to communicate data
clearly and efficiently?
1d. What patterns can
you see? How would
the patterns be easily
recognizable?
1e. What is the highest
temperature in the two
data sets?
1f. What kind of scale or
key would you develop
to include all the data?
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3
1g. How many different
colors would you use
for this data set?
1h. What would the
colors represent?
1i. Can the way data is
represented affect the
way data is interpreted?
2. Make a color scale to
represent the sea surface
temperatures given for
the Pacific Ocean.
3. Plot Data Set 1.
4
4. Plot Data Set 2.
5a. At what latitude and
longitude do the warmest
sea surface temperatures
occur in August during a
non-El Niño year?
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5b. At what latitude and
longitude do the warmest
sea surface temperatures
occur in August during
an El Niño year?
5c. What happens to sea
surface temperatures in
the equatorial Pacific
Ocean during an El Niño
event?
5d. During an El Niño
what are the surface
currents bringing to the
eastern edge of the
Pacific Ocean?
5e. In which direction
are surface currents in
the equatorial Pacific
moving during an El
Niño event?
5f. Which side of the
equatorial Pacific
Ocean would you
expect to have higher
sea level during an
El Niño event?
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5g. Would you infer
that surface circulation
is in the same direction
during El Niño and
non El Niño years?
5h. Are these maps
easier to interpret than
the data table?
5i. In what ways are
the colored maps inferior
to the data table?
5j. Is it important for
scientist to have access
to the map.
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Activity 4
El Niño and Ocean Circulation
Investigate Part B
Page F41
1. Color the maps
2a. Which way did the
warm water move?
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2b. How do you know the
El Niño was at maximum
in November?
2c. How long did it take
for the El Niño to reach
maximum?
2d. How long did it take
for the El Niño to
disappear?
2e. How does this area
affected by El Niño
compare to the size of
your state?
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Activity 4
El Niño and Ocean Circulation
Digging Deeper
Pages F43-46
Peruvian coast
El Niño
Date
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has a strong northwest-flowing
current that causes upwelling,
bringing deep water that is rich in
nutrients up to the surface
lasts one to three years, when the
sea surface temperatures in the
eastern equatorial Pacific Ocean,
off the coast of Peru, are much
higher than other times
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http://esminfo.prenhall.com/science/geoanimations/animati
ons/26_NinoNina.html
Fish population
is much smaller during El Niño,
because cold, nutrient-rich waters
are no longer brought up to the
surface
El Niño
involves changes in ocean
circulation, sea surface
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temperatures, and climate
throughout the entire equatorial
Pacific
El Niño conditions last one to
three years
Non-El Niño conditions last about
five to ten years
Walker circulation
circulation cells within the
equatorial atmosphere caused by
differences in climate
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Air rises up in the western Pacific,
causing abundant rainfall, and
then flows eastward at high
altitudes on the eastern Pacific
It then slowly sinks back to low
altitudes and moves back to the
western Pacific as easterly surface
winds
Changes in the
equatorial Pacific
the areas of humid, rising air and
abundant rain fall shifts eastward,
to the central Pacific and even the
eastern Pacific
The western area is unusually dry
and torrential rains and flooding
along the west coast of South
America
The easterly winds that blow near
the equator weaken, and
sometimes even reverse
The equatorial
Pacific Ocean
(non El Niño)
the easterly winds move warm
surface water toward the western
boundary of the Pacific
The thermocline is much deeper in
the western Pacific than in the
eastern Pacific
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Upwelling along the coast of
South America causes the ocean
surface to be so cold because the
thermocline is very shallow,
allowing the upwelling to tap cold
water from below
The equatorial
Pacific Ocean
(El Niño)
the weakening of the easterly
winds causes warm water to move
eastward from the western Pacific
area, all the way to the west coast
of South America
The thermocline gradually
deepens from west to east
Upwelling continues along the
west coast of South America, but
because the thermocline is now
much deeper there, warm water
instead of cold water is brought up
to the surface
Cause and effect
of El Niño
the changes in the atmospheric
circulation and the changes in the
equatorial ocean that are involved
in the beginning of an El Niño
event seem to develop at about the
same time
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Activity 4
El Niño and Ocean Circulation
Check Your Understanding
Page F46
1. Why is the climate
along the Peruvian
coast of South America
very dry normal nonEl Niño times?
2. How do southerly
winds along the coast
of Peru cause upwelling
there?
3. Why are the oceans
surface waters along
the Peruvian coast of
South America unusually
warm during an El Niño
event, even though
upwelling still operates?
Date
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Activity 4
El Niño and Ocean Circulation
Understanding and Applying
Pages F46-47
1a. What happens to
deep water at the eastern
boundary of the Pacific
Ocean (around 80°W
longitude)
1b. Are there places
where deep water is
exposed to conditions
on the ocean surface?
1c. Are deep water
circulation and surface
water circulation
interconnected in
certain places? Explain.
1d. In which direction
does the surface wind
blow at the Equator?
1e. What explains the
westward spread of cold
surface water off the
coast of North and South
America?
Date
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2a. How do deep
circulation patterns
change in the equatorial
Pacific Ocean?
2b. Are the surface
water temperatures
along the eastern
boundary of the
equatorial Pacific
Ocean warmer or
colder during an
El Niño event?
Explain.
2c. In which direction
does the surface wind
blow at the equator?
2d. What happens to
the location of the
warm surface water
during El Niño?
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Activity 4
El Niño and Ocean Circulation
Inquiring Further
Page F47
1. Technology used to
study ocean-atmosphere
interactions
Investigate the following
El Niño projects:
•TOPEX/Poseidon
•TAO (Tropical
Atmosphere Ocean
Project)
2. La Niña
What is La Niña? What
are the impacts of a La
Niña event? How are
they different from an
El Niño event? Which
do you think affects
your community more?
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