Presentation on theme: " In normal years, atmospheric pressure is greater in the eastern Pacific than in the western Pacific. The trade winds blow surface water from east."— Presentation transcript:
In normal years, atmospheric pressure is greater in the eastern Pacific than in the western Pacific. The trade winds blow surface water from east to west. Warm water "piles up" in the western Pacific and sea level is higher than it is in the east.
Upwelling of cold, nutrient-rich water occurs along the western coast of South America More nutrients = more phytoplankton = food fishing
First noticed off coast of Peru around Christmas, El Niño refers to the Christ child ◦ Occurs every 2 – 7 years Unusual and atmospheric conditions ◦ Trade winds slack off or reverse ◦ Warm water moves eastward ◦ Upwelling slacks off or stops completely
Compare the thermocline from normal conditions (above) to El Niño (below)
Western Pacific (ex. Indonesia) does not get rain ◦ No monsoon season ◦ Drought ◦ Fires Eastern Pacific (ex. South America) ◦ Tropical thunderstorms ◦ Flooding
Opposite effects of El Niño Stronger winds Colder temperatures
El Niño Warmer ocean temps Occurs every 3-7 years Wetter than normal summers Weak trade winds Fewer Atlantic hurricanes La Niña Colder ocean temps Frequency unknown Drier than normal summers Strong trade winds Increased hurricane activity in Atlantic