El Niño/Southern OscillationThe Southern OscillationSlide 3Slide 4Southern Oscillation IndexSouthern OscillationNino RegionsSlide 8Multivariate ENSO IndexWalker CirculationSlide 11Western Pacific Warm PoolCoupled Walker/Ocean CirculationSlide 14El Niño EventsEl Niño ConditionsSlide 17La NinaSlide 19Today…Slide 21Slide 22Altimetry & ENSO StatesEffects of an El NiñoAn El Niño HistorySlide 26Slide 27Slide 28Slide 29Slide 30Slide 31El Niño in AustraliaSlide 33TeleconnectionsEl NiñoEl Niño in the United StatesSlide 37Slide 38Slide 39El Niño & Hurricane DamageSlide 41El Niño & DiseasesDelayed Oscillator TheorySlide 44Slide 45Slide 4697-98 El Niño Event97/98 El NiñoSlide 4997/98 El NiñoSlide 51Slide 52Slide 53Slide 5497/98 El Niño MovieMore readingsEl Niño/Southern Oscillation•Major climatic perturbation on the planet•Coupled atmosphere ocean process •Key is the western tropical Pacific– Ascending branch of the Walker circulation– Potential energy for Kelvin wave pulse•www.pmel.noaa.gov/tao/elnino/nino-home.htmlThe Southern Oscillation •Discovered in 1928 by Sir Gilbert Walker•Links ’s in global climate indices•Proposes a zonal circulation cell over the equatorial PacificThe Southern OscillationThe Southern Oscillation •Pressure ’s regulate strength of the trades•El Niño periods = weak tradesSouthern Oscillation Index•SOI = Tahiti - Darwin air pressure ’s•Low SOI = El Niño conditionsSouthern OscillationNino RegionsMultivariate ENSO Index•Combines observations of air pressure, zonal & meridional components of wind, sea surface temperature, air temperature and total cloudiness.•Positive MEI = ENSO conditionsWalker Circulation•East-to-west pressure gradients drive tradesWalker Circulation•Vertical cell driven by warmest watersWestern Pacific Warm PoolCoupled Walker/Ocean CirculationCoupled Walker/Ocean CirculationEl NiñoEvents•Relaxation of trades causes warm pool to slosh across Pacific basinEl Niño ConditionsEl Niño ConditionsLa Nina•Opposite phase of the ENSO cycle•Intensified trades & Walker circulation•Thermocline undergoes maximum upwellingEL NIÑO/SOUTHERN OSCILLATION (ENSO)DIAGNOSTIC DISCUSSIONissued byCLIMATE PREDICTION CENTER/NCEP10 May 2010A transition from El Niño to ENSO-neutral is underway.Sea surface temperatures are decreasing across much of the Pacific Ocean.Based on current observations and dynamical model forecasts, a transition to ENSO-neutral conditions is expected by June 2010, which will continue into the Northern Hemisphere summer 2010. Although most models predict ENSO-neutral conditions, there is a growing possibility of La Niña developing during the second half of 2010.Today…Today…Altimetry & ENSO States•Most “action” is in the tropical Pacific•Effects are seen in other places– East subtropics– Western NECC regionEffects of an El Niño•Region of ascending air has moved to center of equatorial Pacific•Climate system shifts over 10,000 km to east•Affects the entire planetAn El Niño History•late 1800s Fishermen name El Niño to the periodic warm waters that appear off the coasts of Peru and Ecuador around Christmas.•1928 Gilbert Walker describes the Southern Oscillation.•1957 A large El Niño is observed which affects not just the coasts of Peru and Ecuador but the entire Pacific Ocean.•1969 Jacob Bjerknes links the Southern Oscillation with El Niño events.An El Niño History•1975 Wyrtki uses island sea level to show how eastward flow causes SST’s to rise in east Pacific.•1976 An idealized computer model demonstrates that winds over the far western Pacific can change SST off Peru.•1982 A severe El Niño develops unexpectedly, but is recorded in detail with newly developed ocean buoys.•1985 Several nations launch the Tropical Ocean-Global Atmosphere (TOGA) program.An El Niño History•1986 First coupled model of ocean & atmosphere predicts El Niño event.•1988 Researchers explain how the "memory" of the ocean--the lag between a change in the winds and the response of the ocean--influences terminations of El Niño and the onset of La Niña.•1996-1997 The array of instruments monitoring the Pacific, plus coupled ocean-atmosphere models, enable scientists to warn the public of an impending El Niño event.Coupled Walker/Ocean CirculationEl Niño ConditionsEffects of an El Niño•Places that were wet are now dry and vice versaEffects of an El NiñoEl Niño in AustraliaEl Niño in AustraliaTeleconnections •Discovered in 1928 by Sir Gilbert Walker•Links ’s in global climate indices•Proposes a zonal circulation cell over the equatorial PacificEl Niño•Hadley cells intensify as source of heat is now in central equatorial Pacific•Jet stream intensifies & takes south pathEl Niño in the United StatesEl Niño in the United StatesEl Niño in the United StatesEl Niño in the United StatesEl Niño & Hurricane DamageEl Niño & Hurricane DamageEl Niño & DiseasesDelayed Oscillator Theory•Seeds of El Nino destruction as it starts...Delayed Oscillator TheoryDelayed Oscillator TheoryEl Niño Conditions97-98 El Niño Event97/98 El Niño •At its peak, the 97/98 El Niño was biggest of all time97/98 El Niño97/98 El Niño97/98 El Niño •TOPEX/Poseidon sea level anomaly - December 1, 199797/98 El NiñoOLR = outgoing longwave energy (high OLR = no clouds)97/98 El Niño97/98 El Niño97/98 El Niño MovieMore readings•NOAA ENSO Pagewww.pmel.noaa.gov/tao/elnino/nino-home.html•Review of 97/98 El