11
Activity 4
El Niño and Ocean Circulation
Think About It Date
Page F37 Page #
· 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?
Activity 4
El Niño and Ocean Circulation
Investigate Part A Date
Pages F38-41 Page #
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?
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. 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?
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?
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.
Activity 4
El Niño and Ocean Circulation
Investigate Part B Date
Page F41 Page #
1. Color the maps
2a. Which way did the
warm water move?
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?
Activity 4
El Niño and Ocean Circulation
Digging Deeper Date
Pages F43-46 Page #
Peruvian coast has a strong northwest-flowing current that causes upwelling, bringing deep water that is rich in nutrients up to the surface
El Niño 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
http://esminfo.prenhall.com/science/geoanimations/animations/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 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
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 the areas of humid, rising air and
equatorial Pacific 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 the easterly winds move warm
Pacific Ocean surface water toward the western
(non El Niño) boundary of the Pacific
The thermocline is much deeper in the western Pacific than in the eastern Pacific
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 the weakening of the easterly
Pacific Ocean winds causes warm water to move
(El Niño) 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 the changes in the atmospheric
of El Niño 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
Activity 4
El Niño and Ocean Circulation
Check Your Understanding Date
Page F46 Page #
1. Why is the climate
along the Peruvian
coast of South America
very dry normal non-
El 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?
Activity 4
El Niño and Ocean Circulation
Understanding and Applying Date
Pages F46-47 Page #
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?
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?
Activity 4
El Niño and Ocean Circulation
Inquiring Further Date
Page F47 Page #
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?