1. blow to the west across the tropical pacificTrade winds blow to the west across the tropical pacific Winds pile up warm water in the west pacific so the sea is (1/2 m) higher in Indonesia than EcuadorWinds pile up warm water in the west pacific so the sea is (1/2 m) higher in Indonesia than Ecuador Sea surface is 8°higher in the west than off the coast of S. AmericaSea surface temp is 8°higher in the west than off the coast of S. America S. America receives cold nutrient rich water from events that support high levels of primary productivity-diverse marine organisms- thus an economically stable fishing industryS. America receives cold nutrient rich water from upwelling events that support high levels of primary productivity-diverse marine organisms- thus an economically stable fishing industry follows warm water and therefore is more plentiful in the pacific west than the drier east pacific.Rain follows warm water and therefore is more plentiful in the pacific west than the drier east pacific. NORMAL CONDITIONS

2. weaken or reverse directionTrade winds weaken or reverse direction Depression of the in the east and an increase in the west.Depression of the thermocline in the east and an increase in the west. Warmer water is pushed towards S.Americas coastlineWarmer water is pushed towards S.Americas coastline Restricts nutrient – reduces primary productivityRestricts nutrient upwelling – reduces primary productivity follows the warmer water eastwardRain follows the warmer water eastward El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.

3. Fisheries decline due to the decline of upwelling events and nutrients for primary producers and other marine organisms US – Decrease in Atlantic hurricanes; mild northern & mid west winters; increase in deadly storms in CA & FL Flooding occurs in S. America (Peru) and droughts develop in Indonesia

4. Can follow an El Nino event – cooler water returns & upwellings restored More Atlantic Hurricanes Colder winters in Canada & the Northeast Warmer drier winters in the southeast/west More winter precipitation in the Pacific Northwest Torrential rains in Southeast Asia Increase in tornado activity and wildfires in US