APES Unit 4: El Nino

what is el nino (southern ocillation)

-occurs every 2-7 years in the Pacific ocean (near the equator)
-prevailing ("normal") trade winds that blow westward weaken or reverse direction.
-surface waters near South American coasts warm up.
-nutrient-rich upwellings (vertical flow of colder, deeper water) are suppressed.

what are the effects of el nino?

-Sea surface temperatures warm up near western South American coasts.
-The decrease of nutrient upwellings robs phytoplankton of needed minerals, resulting in a decrease in primary productivity (photosynthesis), leading to a decrease in overall fish pop.
-Philippines, Indonesia, and Australia are dryer than normal (droughts)
-U.S. and Canada experience warmer winters.
-Eastern U.S., Peru, Ecuador, & the tropics have higher than average rainfall (flooding)

what is la nina?

-occurs when westerly trade winds get stronger, and increased upwellings lead to colder waters off coast of South America.
-la niña typically contributes to a lower global average temperature than do El niño conditions.
-la niña can mean more Atlantic hurricanes, colder winters in Canada and northeastern U.S., and wetter winters in Pacific northwest, & more rain in southeast Asia.