Name _________________________ Period _____
Earth’s Fluid Spheres - Oceans
Activity 4 – El Niño and Ocean Circulation
Objective Question: What is El Niño?
Initial thoughts:
Final thoughts:
Normally, the trade winds blow from ___________to _____________, dragging the warm surface waters
__________________, where they accumulate into a large, deep pool just east of Indonesia, and northeast
of Australia. Meanwhile, the deeper, colder waters in the eastern Pacific are allowed to rise to the surface,
creating an east-west temperature gradient along the equator known as the ________________________
tilt. Sometimes, and for reasons not fully understood, the trade winds _________________ direction to
blow from west to east. When this happens, the ocean responds in a several ways. Warm surface waters
from the large, warm pool east of Indonesia begin to move ___________________. Beneath the surface,
the thermocline along the equator flattens as the warm waters at the surface prevent the colder, deeper
waters from _________________. As a result, the large central and eastern Pacific regions ____________
into an El Niño.
The ____________________ __________________________ refers to the fluctuation in atmospheric
pressure. During El Nino, when the warm oceanic phase is in effect, surface pressures in the western
Pacific are __________ (colder than normal air), and when the cold phase is in effect (La Niña), surface
pressures in the western Pacific are _____________ (lots of hot air).
The effects of El Niño in South America are direct and stronger than in North America. An El Niño is
associated with ___________ and very ____________ summers (December-February) along the coasts of
northern Peru and Ecuador, causing major ____________________ whenever the event is strong or
extreme. The effects during the months of February, March and April may become critical. Along the
west coast of South America, El Niño reduces the upwelling of cold, nutrient-rich water that sustains large
_________ populations so the fishing industry suffers.
In North America, El Niño creates _______________-than-average winters in the upper Midwest states
and the Northwest, thus _______________ snowfall than average during winter. Meanwhile, central and
southern California, northwest Mexico and the southwestern U.S. become significantly ____________.
Part B – Extent and duration of an El Niño Event
Walker circulation
Southern Oscillation
Digging Deeper for Activity 4 – El Niño and Ocean Circulation
Do NOT feel limited by the space given here! If you need more room to answer the questions, please attach more paper.
Questions While Reading (If you don’t have any, you’re not reading critically!)
Check Your Understanding (CSIQ format)
Understanding and Applying (CSIQ format)
Conclusion : Use the TOPEX remotely sensed data to answer Objective Question using the “formula” Claim +
Evidence + Reasoning = Explanation