AP Environmental Science El Niño
Past Largest El Niño Storms
1982-1983 & 1997-1998
Weather Impacts 1997-1998 (Hurricane Season)
1997 had low number of hurricanes; extreme wind shear caused unfavorable conditions for storm development (lack of shear made them unable to form)
Effects of La Niña
Central North America: increased storminess and precipitation, increased frequency of cold air outbreaks, colder than normal winters; Southeastern US: less stormy and less precipitation, warmer than normal conditions and winters
ENSO
El Niño Southern Oscillation
Weather and Climate Effects
Unusual warming of eastern Pacific ocean; trade winds blow east to west and are weakening; thunderstorms are a common effect (islands with mild weather suddenly have terrible storms); cloud and rain storms shift to the east; rain falls in usually dry areas, causing droughts and forest fires; earth's atmosphere produces high and low pressure systems; temperature rise in Canada and upper plains of US, temperature drop in southern areas of US
Lessons Learned
Unpredictable and stronger than ever; funding went into research and emphasis on better prediction and planning; landslides, mudslides, flooding, very cold weather in Southern US
What is El Niño?
A warm current of water; a disruption of the ocean-atmospheric system in the tropical Pacific having important consequences in weather around the world
Economic Impacts of El Niño
Agriculture, construction, energy distribution, and outdoor recreation are affected; South American economies are curtailed by loss of fishing and climate effects on crops; Asia and Western Pacific have droughts and starving crops; heavy effects on farming and properties; impacts sales, revenue, and employment in climate sensitive industries
When It Occurs
Around Christmas, where it got its name from; lasts 3-7 months or up to a few years
The Consequences of El Niño
Increased rainfall in southern tier of US and in Peru, causing flooding; could cause droughts on eastern coast of Asia and in Australia (fires); marine life is reduced
Winter & Flooding in 1998
Major ice storm affected numerous states; massive flooding and erosion from storms coming onshore
Indicator Species
Species that we look to see a spike in deaths that represent the health of the whole ecosystem; ex: manatees
El Niño Conditions
Trade winds are weakened, allowing warm western Pacific waters to move east and reach South American coasts that makes the thermocline (layer between surface water and deep water) deeper; nutrient rich waters on the coasts are depleted by warmer waters because thermocline is deeper
Normal Conditions
Trade winds blow west across tropical Pacific, pile up warm surface water in west Pacific so the sea surface is about half a meter higher in Indonesia than Ecuador; water is 8 degrees celsius warmer in western Pacific; usually moves warm water towards instead of away from Asia, making it typically have a lot of rain
La Niña's Effects
more snow across Eastern Alaska, weather in LA is more severe, effects are opposite of El Niño
What Happens with La Niña
normal weather; sea and sea surface temperatures fall; usually lasts between 9-12 months and up to 2 years;
La Niña
opposite of El Niño; climactic fluctuation involving abnormal cooling of waters off of Peru and Ecuador; unusually cold ocean temperatures around equator, some consider it normal conditions
