El Nino

What is El Niño? Warm current of water Disruption of the ocean-atmosphere system in the tropical Pacific Important consequences in weather around the globe.

The Consequences of El Niño Increased Rainfall across the southern tier of the US and in Peru causing flooding Could cause droughts on the western coast and Australia This leads to brush fires in Australia Marine life is reduced

Normal Conditions Trade winds blow west across the tropical pacific Pile up warm surface water in the western Pacific Sea surface about a half meter higher at Indonesia than Ecuador. Water is 8oC warmer in the western Pacific

El Niño Conditions Trade winds are weakened Allows warmer western Pacific waters to move east and reach the South American coasts Makes thermocline (layer between surface water and deep water) deeper. Results, nutrient rich waters on the coasts are depleted by the warmer waters

When it occurs Around Christmas time every year Happens off the coast of Ecuador and Peru Lasts about a month Occur every three to seven years Some El Niño's may even last for a couple years

Effects are extensive and have impact on nations all over the world. Effects of El Nino Effects are extensive and have impact on nations all over the world. http://www.bom.gov.au/climate/glossary/elnino/shtml

El Nino Weather & Climate Unusual warming of Western Pacific Ocean. Warming caused by trade winds blowing from East to West. Thunderstorms common effect in tropical regions (Severe Thunderstorm over Strands Beach, Dana Point) http://www.aku-aku.com/html/Local_stock/el-nino_JPG.htm

Forest fires and drought in the Western Pacific, flooding in South America. Temperatures rise in western Canada and the upper plains of the U.S., while the southern U.S. experiences colder than normal temperatures (Rainforest fire in Brazil) (Flooding in Santa Cruz River) http://geochange.er.usgs.gov/sw/changes/natural/elnino/

Economic Impacts of El Nino Weather and climate sensitive industries such as agriculture, construction, energy distribution, and outdoor recreation are directly impacted by El Nino. South American economies are curtailed by the loss of fishing and climate effects on crops and people. In Asia and the western Pacific region, severe droughts occur which starve crops as well as people and the economy. Extreme climate changes occurring in North America such as flooding and droughts, bring economic damage to the United States.

What happens during La Nina? Climactic fluctuation involving the abnormal cooling of waters off of Peru and Ecuador Temperatures of subsurface waters in the tropical Pacific are cooler than normal Brought to the surface by atmospheric and oceanic waves moving Easterly. Sea-surface temperatures along the Equator can fall by up to 2oC Effects are most clearly seen during the wintertime (as are El Nino’s) La Nina usually lasts between 9 and 12 months, but some have lasted up to 2 years

Sea Surface Temperatures El Nino (December 1997) Sea Surface Temperatures La Nina (December 2000)

Effects of La Nina In large portions of Central North America: Increased storms and precipitation Increased frequency of significant cold-air outbreaks (Colder temperatures) Colder than normal winters Southeastern US: Less storms and precipitation Warmer than normal conditions Warmer than normal winters

La Nina’s Effects More snow across Eastern Alaska Jet stream runs from the central Rockies to the central Great Lakes Weather during La Nina is more severe further North and West During El Nino, more severe weather is from the northern Gulf of Mexico to northern Florida (where the jet stream is during it) La Nina’s effects are the opposite of El Nino’s i.e. Australian and Indonesian areas are wetter than normal (whereas with El Nino, they were very dry)