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 ____________. Investigation Part B – Extent and duration of an El Niño Event 1. 2a. 2b. 2c. 2d. 2e. GeoWords 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!) 1. Check Your Understanding (CSIQ format) 1. 2. 3. Understanding and Applying (CSIQ format) 1a. 1d. 1e. 2a. 2b. 2c. Conclusion : Use the TOPEX remotely sensed data to answer Objective Question using the “formula” Claim + Evidence + Reasoning = Explanation