El Niño is the warm phase of the El Niño Southern Oscillation (commonly called ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (between approximately the International Date Line and 120°W), including off the Pacific coast of South America. El Niño Southern Oscillation refers to the cycle of warm and cold temperatures, as measured by sea surface temperature, SST, of the tropical central and eastern Pacific Ocean. El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. The cool phase of ENSO is called "La Niña" with SST in the eastern Pacific below average and air pressures high in the eastern and low in western Pacific. The ENSO cycle, both El Niño and La Niña, causes global changes of both temperatures and rainfall. Mechanisms that cause the oscillation remain under study.
Developing countries dependent upon agriculture and fishing, particularly those bordering the Pacific Ocean, are the most affected. In Spanish, the capitalized term "El Niño" refers to the Christ child, Jesus (literal translation "The (male) Child"). La Niña, chosen as the 'opposite' of El Niño, literally means "The (female) Child". El Niño was so named because periodic warming in the Pacific near South America is often noticed around Christmas.
- 1 Definition
- 2 Effects of ENSO warm phase (El Niño)
- 3 Transitional phases
- 4 Recent occurrences
- 5 Remote influence on tropical Atlantic Ocean
- 6 Global warming
- 7 El Niño diversity
- 8 Health and social impacts of El Niño
- 9 Cultural history and prehistoric information
- 10 Climate networks
- 11 See also
- 12 References
- 13 Further reading
- 14 External links
El Niño is defined by prolonged warming in the Pacific Ocean sea surface temperatures when compared with the average value. The U.S NOAA definition is a 3-month average warming of at least 0.5 °C (0.9 °F) in a specific area of the east-central tropical Pacific Ocean, other organizations define the term slightly differently. Typically, this anomaly happens at irregular intervals of two to seven years, and lasts nine months to two years. The average period length is five years. When this warming occurs for seven to nine months, it is classified as El Niño "conditions"; when its duration is longer, it is classified as an El Niño "episode".
- Rise in surface pressure over the Indian Ocean, Indonesia, and Australia
- Fall in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean
- Trade winds in the south Pacific weaken or head east
- Warm air rises near Peru, causing rain in the northern Peruvian deserts
El Niño's warm rush of nutrient-poor water heated by its eastward passage in the Equatorial Current, replaces the cold, nutrient-rich surface water of the Humboldt Current. When El Niño conditions last for many months, extensive ocean warming and the reduction in easterly trade winds limits upwelling of cold nutrient-rich deep water, and its economic impact to local fishing for an international market can be serious.
More generally, El Niño can affect commodity prices and the macroeconomy of different countries - and not always for the worst. It can constrain the supply of rain-driven agricultural commodities; reduce agricultural output, construction, and services activities; create food-price and generalised inflation; and may trigger social unrest in commodity-dependent poor countries that primarily rely on imported food. A University of Cambridge Working Paper shows that while Australia, Chile, Indonesia, India, Japan, New Zealand and South Africa face a short-lived fall in economic activity in response to an El Niño shock, other countries may actually benefit from an El Niño weather shock (either directly or indirectly through positive spillovers from major trading partners), for instance, Argentina, Canada, Mexico and the United States. Furthermore, most countries experience short-run inflationary pressures following an El Niño shock, while global energy and non-fuel commodity prices increase.
Effects of ENSO warm phase (El Niño)
Because El Niño's warm pool feeds thunderstorms above, it creates increased rainfall across the east-central and eastern Pacific Ocean, including several portions of the South American west coast. The effects of El Niño in South America are direct and stronger than in North America. An El Niño is associated with warm and very wet weather months in April–October along the coasts of northern Peru and Ecuador, causing major flooding whenever the event is strong or extreme. The effects during the months of February, March, and April may become critical. Along the west coast of South America, El Niño reduces the upwelling of cold, nutrient-rich water that sustains large fish populations, which in turn sustain abundant sea birds, whose droppings support the fertilizer industry. The reduction in upwelling leads to fish kills off the shore of Peru.
The local fishing industry along the affected coastline can suffer during long-lasting El Niño events. The world's largest fishery collapsed due to overfishing during the 1972 El Niño Peruvian anchoveta reduction. During the 1982–83 event, jack mackerel and anchoveta populations were reduced, scallops increased in warmer water, but hake followed cooler water down the continental slope, while shrimp and sardines moved southward, so some catches decreased while others increased. Horse mackerel have increased in the region during warm events. Shifting locations and types of fish due to changing conditions provide challenges for fishing industries. Peruvian sardines have moved during El Niño events to Chilean areas. Other conditions provide further complications, such as the government of Chile in 1991 creating restrictions on the fishing areas for self-employed fishermen and industrial fleets.
The ENSO variability may contribute to the great success of small, fast-growing species along the Peruvian coast, as periods of low population removes predators in the area. Similar effects benefit migratory birds that travel each spring from predator-rich tropical areas to distant winter-stressed nesting areas.
Southern Brazil and northern Argentina also experience wetter than normal conditions, but mainly during the spring and early summer. Central Chile receives a mild winter with large rainfall, and the Peruvian-Bolivian Altiplano is sometimes exposed to unusual winter snowfall events. Drier and hotter weather occurs in parts of the Amazon River Basin, Colombia, and Central America.
Winters, during the El Niño effect, are warmer and drier than average in the Northwest, northern Midwest, and upper Northeast United States, so those regions experience reduced snowfalls. Meanwhile, significantly wetter winters are present in northwest Mexico and the southwest United States, including central and southern California, while both cooler and wetter than average winters in northeast Mexico and the southeast United States (including the Tidewater region of Virginia) occur during the El Niño phase of the oscillation.
Some believed the ice storm in January 1998, which devastated parts of New England, southern Ontario and southern Quebec, was caused or accentuated by El Niño's warming effects. El Niño warmed Vancouver for the 2010 Winter Olympics, such that the area experienced a warmer than average winter during the games.
The synoptic condition for the Tehuantepecer is associated with high-pressure system forming in Sierra Madre of Mexico in the wake of an advancing cold front, which causes winds to accelerate through the Isthmus of Tehuantepec. Tehuantepecers primarily occur during the cold season months for the region in the wake of cold fronts, between October and February, with a summer maximum in July caused by the westward extension of the Azores High. Wind magnitude is greater during El Niño years than during La Niña years, due to the more frequent cold frontal incursions during El Niño winters. Its effects can last from a few hours to six days. El Niño is credited with suppressing Atlantic hurricanes, and made the 2009 Atlantic hurricane season the least active in 12 years.
Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies. When the subtropical ridge position shifts due to El Niño, so will the preferred tropical cyclone tracks. Areas west of Japan and Korea tend to experience much fewer September–November tropical cyclone impacts during El Niño and neutral years. During El Niño years, the break in the subtropical ridge tends to lie near 130°E, which would favor the Japanese archipelago. During El Niño years, Guam's chance of a tropical cyclone impact is one-third higher than the long-term average. The tropical Atlantic ocean experiences depressed activity due to increased vertical wind shear across the region during El Niño years. On the flip side, however, the tropical Pacific Ocean east of the dateline has above-normal activity during El Niño years due to water temperatures well above average and decreased windshear. Most of the recorded East Pacific category 5 hurricanes occur during El Niño years in clusters.
In Africa, East Africa — including Kenya, Tanzania, and the White Nile basin — experiences, in the long rains from March to May, wetter-than-normal conditions. Conditions are also drier than normal from December to February in south-central Africa, mainly in Zambia, Zimbabwe, Mozambique, and Botswana. Direct effects of El Niño resulting in drier conditions occur in parts of Southeast Asia and Northern Australia, increasing bush fires, worsening haze, and decreasing air quality dramatically. Drier-than-normal conditions are also in general observed in Queensland, inland Victoria, inland New South Wales, and eastern Tasmania from June to August.
Many ENSO linkages exist in the high southern latitudes around Antarctica. Specifically, El Niño conditions result in high pressure anomalies over the Amundsen and Bellingshausen Seas, causing reduced sea ice and increased poleward heat fluxes in these sectors, as well as the Ross Sea. The Weddell Sea, conversely, tends to become colder with more sea ice during El Niño. The exact opposite heating and atmospheric pressure anomalies occur during La Niña. This pattern of variability is known as the Antarctic dipole mode, although the Antarctic response to ENSO forcing is not ubiquitous.
El Niño's effects on Europe appear to be strongest in winter. Recent evidence indicates that El Niño causes a colder, drier winter in Northern Europe and a milder, wetter winter in Southern Europe. The El Niño winter of 2009/10 was extremely cold in Northern Europe but El Niño is not the only factor at play in European winter weather and the weak El Niño winter of 2006/2007 was unusually mild in Europe, and the Alps recorded very little snow coverage that season.
As warm water spreads from the west Pacific and the Indian Ocean to the east Pacific, it takes the rain with it, causing extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific. Singapore experienced the driest February in 2014 since records began in 1869, with only 6.3 mm of rain falling in the month and temperatures hitting as high as 35 °C on 26 February. The years 1968 and 2005 had the next driest Februaries, when 8.4 mm of rain fell.
Transitional phases at the onset or departure of El Niño or La Niña can also be important factors on global weather by affecting teleconnections. Significant episodes, known as Trans-Niño, are measured by the Trans-Niño index (TNI). Examples of affected short-time climate in North America include precipitation in the Northwest US and intense tornado activity in the contiguous US.
During strong El Niño episodes, a secondary peak in sea surface temperature across the far eastern equatorial Pacific Ocean sometimes follows the initial peak.
In December 2014, the Japan Meteorological Agency had declared the onset of El Niño conditions, as warmer than normal sea surface temperatures were measured over the Pacific, albeit citing the lack of atmospheric conditions related to the event. Months later both Climate Prediction Center and Australian Bureau of Meteorology had declared the arrival of weak El Niño conditions, in March and May 2015, respectively. Current El Niño conditions are forecast to intensify into strong conditions by fall and winter of 2015.
Remote influence on tropical Atlantic Ocean
A study of climate records has shown that El Niño events in the equatorial Pacific are generally associated with a warm tropical North Atlantic in the following spring and summer. About half of El Niño events persist sufficiently into the spring months for the Western Hemisphere Warm Pool to become unusually large in summer. Occasionally, El Niño's effect on the Atlantic Walker circulation over South America strengthens the easterly trade winds in the western equatorial Atlantic region. As a result, an unusual cooling may occur in the eastern equatorial Atlantic in spring and summer following El Niño peaks in winter. Cases of El Niño-type events in both oceans simultaneously have been linked to severe famines related to the extended failure of monsoon rains.
During the last several decades the number of El Niño events increased, although a much longer period of observation is needed to detect robust changes. The question is, or was, whether this is a random fluctuation or a normal instance of variation for that phenomenon or the result of global climate changes as a result of global warming. A robust tendency to increase in extreme El Niños was reported in Nature 2014.
Several studies of historical data suggest the recent El Niño variation is linked to global warming but there is no consensus on this aspect. For example, even after subtracting the positive influence of decadal variation, is shown to be possibly present in the ENSO trend, the amplitude of the ENSO variability in the observed data still increases, by as much as 60% in the last 50 years.
It may be that the observed phenomenon of more frequent and stronger El Niño events occurs only in the initial phase of the global warming, and then (e.g., after the lower layers of the ocean get warmer, as well), El Niño will become weaker than it was. It may also be that the stabilizing and destabilizing forces influencing the phenomenon will eventually compensate for each other. More research is needed to provide a better answer to that question. However, new models published in Nature 2014 indicated unmitigated global warming would particularly affect the surface waters of the eastern equatorial Pacific and double extreme El Niño occurrence.
El Niño diversity
The traditional Niño, also called Eastern Pacific (EP) El Niño, involves temperature anomalies in the Eastern Pacific. However, in the last two decades, nontraditional El Niños were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) El Niño, "dateline" El Niño (because the anomaly arises near the dateline), or El Niño "Modoki" (Modoki is Japanese for "similar, but different"). There are flavors of ENSO additional to EP and CP types and some scientists argue that ENSO exists as a continuum often with hybrid types.
The effects of the CP El Niño are different from those of the traditional EP El Niño—e.g., the recently discovered El Niño leads to more hurricanes more frequently making landfall in the Atlantic.
The recent discovery of El Niño Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. More research must be done to find the correlation and study past El Niño episodes. More generally, there is no scientific consensus on how/if climate change may affect ENSO.
There is also a scientific debate on the very existence of this "new" ENSO. Indeed, a number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO.
The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986. Recent Central Pacific El Niños happened in 1986–1987, 1991–1992, 1994–1995, 2002–2003, 2004–2005 and 2009–2010. Furthermore, there were "Modoki" events in 1957–59, 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80.
Extreme weather conditions related to the El Niño cycle correlate with changes in the incidence of epidemic diseases. For example, the El Niño cycle is associated with increased risks of some of the diseases transmitted by mosquitoes, such as malaria, dengue, and Rift Valley fever. Cycles of malaria in India, Venezuela, Brazil, and Colombia have now been linked to El Niño. Outbreaks of another mosquito-transmitted disease, Australian encephalitis (Murray Valley encephalitis—MVE), occur in temperate south-east Australia after heavy rainfall and flooding, which are associated with La Niña events. A severe outbreak of Rift Valley fever occurred after extreme rainfall in north-eastern Kenya and southern Somalia during the 1997–98 El Niño.
ENSO may be linked to civil conflicts. Scientists at The Earth Institute of Columbia University, having analyzed data from 1950 to 2004, suggest ENSO may have had a role in 21% of all civil conflicts since 1950, with the risk of annual civil conflict doubling from 3% to 6% in countries affected by ENSO during El Niño years relative to La Niña years.
Cultural history and prehistoric information
ENSO conditions have occurred at two- to seven-year intervals for at least the past 300 years, but most of them have been weak. Evidence is also strong for El Niño events during the early Holocene epoch 10,000 years ago.
El Niño affected pre-Columbian Incas  and may have led to the demise of the Moche and other pre-Columbian Peruvian cultures. A recent study suggests a strong El-Niño effect between 1789 and 1793 caused poor crop yields in Europe, which in turn helped touch off the French Revolution. The extreme weather produced by El Niño in 1876–77 gave rise to the most deadly famines of the 19th century. The 1876 famine alone in northern China killed up to 13 million people.
An early recorded mention of the term "El Niño" to refer to climate occurred in 1892, when Captain Camilo Carrillo told the geographical society congress in Lima that Peruvian sailors named the warm north-flowing current "El Niño" because it was most noticeable around Christmas. The phenomenon had long been of interest because of its effects on the guano industry and other enterprises that depend on biological productivity of the sea.
Charles Todd, in 1893, suggested droughts in India and Australia tended to occur at the same time; Norman Lockyer noted the same in 1904. An El Niño connection with flooding was reported in 1895 by Pezet and Eguiguren. In 1924, Gilbert Walker (for whom the Walker circulation is named) coined the term "Southern Oscillation".
The major 1982–83 El Niño led to an upsurge of interest from the scientific community. The period 1991–1995 was unusual in that El Niños have rarely occurred in such rapid succession. An especially intense El Niño event in 1998 caused an estimated 16% of the world's reef systems to die. The event temporarily warmed air temperature by 1.5 °C, compared to the usual increase of 0.25 °C associated with El Niño events. Since then, mass coral bleaching has become common worldwide, with all regions having suffered "severe bleaching".
Analysis of El Niño events using climate networks shows the dynamics of the climate network is very sensitive to El Niño events. Many links in the network fail during El Niño events.
- Arctic oscillation
- Benguela Niño
- Indian Ocean Dipole
- Pacific Decadal Oscillation
- North Atlantic Oscillation
- Multivariate ENSO index
- 1997 Pacific typhoon season
- 2015 Pacific typhoon season
- 2015 heat wave in India
- "Independent NASA Satellite Measurements Confirm El Niño is Back and Strong". NASA/JPL.
- Climate Prediction Center (2005-12-19). "Frequently Asked Questions about El Niño and La Niña". National Centers for Environmental Prediction. Retrieved 2009-07-17.
- K.E. Trenberth, P.D. Jones, P. Ambenje, R. Bojariu , D. Easterling, A. Klein Tank, D. Parker, F. Rahimzadeh, J.A. Renwick, M. Rusticucci, B. Soden and P. Zhai. "Observations: Surface and Atmospheric Climate Change". In Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press. pp. 235–336.
- "El Niño Information". California Department of Fish and Game, Marine Region.
- Nathaniel C. Johnson 2014: Atmospheric Science: A boost in big El Niño Nature Climate Change 4, 90–91 (2014) doi:10.1038/nclimate2108 Published online 29 January 2014. Seen 20 May 2015. http://www.nature.com/nclimate/journal/v4/n2/full/nclimate2108.html
- Wenju Cai, Simon Borlace, Matthieu Lengaigne, Peter van Rensch, Mat Collins, Gabriel Vecchi, Axel Timmermann, Agus Santoso, Michael J. McPhaden, Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin 2013: Increasing frequency of extreme El Niño events due to greenhouse warming. Nature Climate Change 4, 111–116 (2014) doi:10.1038/nclimate2100 Received 15 October 2013 Accepted 11 December 2013 Published online 19 January 2014. Seen 20 May 2015. http://www.nature.com/nclimate/journal/v4/n2/full/nclimate2100.html
- Climate Prediction Center (2005-12-19). "ENSO FAQ: How often do El Niño and La Niña typically occur?". National Centers for Environmental Prediction. Retrieved 2009-07-26.
- National Climatic Data Center (June 2009). "El Niño / Southern Oscillation (ENSO) June 2009". National Oceanic and Atmospheric Administration. Retrieved 2009-07-26.
- Intergovernmental Panel on Climate Change (2007). "Climate Change 2007: Working Group I: The Physical Science Basis: 3.7 Changes in the Tropics and Subtropics, and in the Monsoons". World Meteorological Organization. Retrieved 2014-07-01.
- WW2010 (1998-04-28). "El Niño". University of Illinois at Urbana-Champaign. Retrieved 2009-07-17.
- "Study reveals economic impact of El Niño". University of Cambridge. 2014-07-11. Retrieved 2014-07-25.
- Cashin, Paul; Mohaddes, Kamiar & Raissi, Mehdi (2014). "Fair Weather or Foul? The Macroeconomic Effects of El Niño" (PDF). Cambridge Working Papers in Economics.
- "Atmospheric Consequences of El Niño". University of Illinois. Retrieved 2010-05-31.
- Pearcy, W. G.; Schoener, A. (1987). "Changes in the marine biota coincident with the 1982-1983 El Niño in the northeastern subarctic Pacific Ocean". Journal of Geophysical Research 92 (C13): 14417–28. Bibcode:1987JGR....9214417P. doi:10.1029/JC092iC13p14417.
- Climate Prediction Center. Average October-December (3-month) Temperature Rankings During ENSO Events. Retrieved 2008-04-16.
- Climate Prediction Center. Average December-February (3-month) Temperature Rankings During ENSO Events. Retrieved 2008-04-16.
- Climate change | Issues | David Suzuki Foundation. Davidsuzuki.org (2013-04-18). Retrieved 2013-06-15.
- Vancouver 2010 to Be Warmest Winter Olympics Yet
- Rosario Romero-Centeno, Jorge Zavala-Hidalgo, Artemio Gallegos, and James J. O’Brien (August 2003). "Isthmus of Tehuantepec wind climatology and ENSO signal". Journal of Climate 16 (15): 2628–2639. Bibcode:2003JCli...16.2628R. doi:10.1175/1520-0442(2003)016<2628:iotwca>2.0.co;2 (inactive 2015-01-12).
- Paul A. Arnerich. "Tehuantepecer Winds of the West Coast of Mexico". Mariners Weather Log (National Oceanic and Atmospheric Administration) 15 (2): 63–67.
- Brian K. Sullivan (2010-05-06). "El Niño Warning Will Fade Out by June, U.S. Says (Update 1)". Bloomberg Businessweek. Retrieved 2010-05-31.
- Joint Typhoon Warning Center (2006). 3.3 JTWC Forecasting Philosophies. United States Navy. Retrieved 2007-02-11.
- M. C. Wu, W. L. Chang, and W. M. Leung (2003). Impacts of El Niño–Southern Oscillation Events on Tropical Cyclone Landfalling Activity in the Western North Pacific. Journal of Climate: pp. 1419–1428. Retrieved 2007-02-11.
- Pacific ENSO Applications Climate Center. Pacific ENSO Update: 4th Quarter, 2006. Vol. 12 No. 4. Retrieved 2008-03-19.
- Edward N. Rappaport (September 1999). "Atlantic Hurricane Season of 1997" (PDF). Monthly Weather Review 127 (9): 2012–2026. Bibcode:1999MWRv..127.2012R. doi:10.1175/1520-0493(1999)127<2012:AHSO>2.0.CO;2 (inactive 2015-01-12). ISSN 1520-0493. Retrieved 2009-07-18.
- Climate Prediction Center — Expert Assessments: East Pacific Hurricane Outlook Background Information. Cpc.ncep.noaa.gov (2013-05-23). Retrieved 2013-06-15.
- Turner, John (2004). "The El Niño–Southern Oscillation and Antarctica". International Journal of Climatology 24: 1–31. Bibcode:2004IJCli..24....1T. doi:10.1002/joc.965 (inactive 2015-01-12).
- Yuan, Xiaojun (2004). "ENSO-related impacts on Antarctic sea ice: a synthesis of phenomenon and mechanisms". Antarctic Science 16 (4): 415–425. doi:10.1017/S0954102004002238.
- S.Ineson and A.A.Scaife (2009). "The role of the stratosphere in the European climate response to El Niño". Nature Geoscience 2 (1): 32–36. doi:10.1038/ngeo381.
- "Concern over Europe 'snow crisis'". BBC News. 2006-12-17. Retrieved 2010-05-01.
- [dead link]
- Trenberth, Kevin E.; D. P. Stepaniak (2001). "Indices of El Niño Evolution". J. Climate 14 (8): 1697–701. Bibcode:2001JCli...14.1697T. doi:10.1175/1520-0442(2001)014<1697:LIOENO>2.0.CO;2 (inactive 2015-01-12). ISSN 1520-0442.
- Kennedy, Adam M.; D. C. Garen; R. W. Koch (2009). "The association between climate teleconnection indices and Upper Klamath seasonal streamflow: Trans-Niño Index". Hydrol. Process. 23 (7): 973–84. Bibcode:2009HyPr...23..973K. doi:10.1002/hyp.7200.
- Lee, Sang-Ki; R. Atlas; D. Enfield; C. Wang; H. Liu (2013). "Is there an optimal ENSO pattern that enhances large-scale atmospheric processes conducive to tornado outbreaks in the U.S?". J. Climate 26 (5): 1626–1642. Bibcode:2013JCli...26.1626L. doi:10.1175/JCLI-D-12-00128.1.
- Kim, WonMoo; Wenju Cai (2013). "Second peak in the far eastern Pacific sea surface temperature anomaly following strong El Niño events". Geophys. Res. Lett. 40 (17): n/a. Bibcode:2013GeoRL..40.4751K. doi:10.1002/grl.50697 (inactive 2015-01-12).
- Historical El Niño/La Niña Episodes (1950-present), Climate Prediction Center, NOAA
- El Niño and La Niña Years and Intensities, Jan Null, CCM 07-10-14
- El Nino Outlook
-  El Nino Advisory
- El Niño in the tropical Pacific
- Enfield, David B.; Mayer, Dennis A. (1997). "Tropical Atlantic sea surface temperature variability and its relation to El Niño–Southern Oscillation". Journal of Geophysical Research 102 (C1): 929–945. Bibcode:1997JGR...102..929E. doi:10.1029/96JC03296.
- Lee, Sang-Ki, Chunzai Wang and David B. Enfield (2008). "Why do some El Niños have no impact on tropical North Atlantic SST?". Geophysical Research Letters 35 (L16705): L16705. Bibcode:2008GeoRL..3516705L. doi:10.1029/2008GL034734 (inactive 2015-01-12). Retrieved 2014-01-15.
- Latif, M.; GröTzner, A. (2000). "The equatorial Atlantic oscillation and its response to ENSO". Climate Dynamics 16 (2–3): 213–218. Bibcode:2000ClDy...16..213L. doi:10.1007/s003820050014 (inactive 2015-01-12).
- Davis, Mike (2001). Late Victorian Holocausts: El Niño Famines and the Making of the Third World. London: Verso. p. 271. ISBN 1-85984-739-0.
- Trenberth, Kevin E.; Hoar, Timothy J. (January 1996). "The 1990–1995 El Niño–Southern Oscillation event: Longest on record". Geophysical Research Letters 23 (1): 57–60. Bibcode:1996GeoRL..23...57T. doi:10.1029/95GL03602.
- Wittenberg, A.T. (2009). "Are historical records sufficient to constrain ENSO simulations?". Geophys. Res. Lett. 36 (12): L12702. Bibcode:2009GeoRL..3612702W. doi:10.1029/2009GL038710.
- Nathaniel C. Johnson 2014: Atmospheric Science: A boost in big El Niño Nature Climate Change 4, 90–91 (2014) doi:10.1038/nclimate2108 Published online 29 January 2014. http://www.nature.com/nclimate/journal/v4/n2/full/nclimate2108.html
- Fedorov, Alexey V.; Philander, S. George (2000). "Is El Niño Changing?". Science 288 (5473): 1997–2002. Bibcode:2000Sci...288.1997F. doi:10.1126/science.288.5473.1997 (inactive 2015-01-12). PMID 10856205.
- Zhang, Qiong; Guan, Yue; Yang, Haijun (2008). "ENSO Amplitude Change in Observation and Coupled Models". Advances in Atmospheric Sciences 25 (3): 331–6. Bibcode:2008AdAtS..25..361Z. doi:10.1007/s00376-008-0361-5.
- Meehl, G. A.; Teng, H.; Branstator, G. (2006). "Future changes of El Niño in two global coupled climate models". Climate Dynamics 26 (6): 549. Bibcode:2006ClDy...26..549M. doi:10.1007/s00382-005-0098-0.
- Philip, S.; Van Oldenborgh, G. J. (2006). "Shifts in ENSO coupling processes under global warming". Geophysical Research Letters 33 (11). Bibcode:2006GeoRL..3311704P. doi:10.1029/2006GL026196.
- Kao, Hsun-Ying and Jin-Yi Yu (2009). "Contrasting Eastern-Pacific and Central-Pacific Types of ENSO". J. Climate 22 (3): 615–632. Bibcode:2009JCli...22..615K. doi:10.1175/2008JCLI2309.1.
- Larkin, N. K.; Harrison, D. E. (2005). "On the definition of El Niño and associated seasonal average U.S. Weather anomalies". Geophysical Research Letters 32 (13): L13705. Bibcode:2005GeoRL..3213705L. doi:10.1029/2005GL022738.
- Ashok, K., S. K. Behera, S. A. Rao, H. Weng, and T. Yamagata (2007). "El Nino Modoki and its possible teleconnection". Journal of Geophysical Research (J. Geophys. Res.) 112: C11007. Bibcode:2007JGRC..11211007A. doi:10.1029/2006JC003798.
- Weng, H., K. Ashok, S. K. Behera, S. A. Rao, and T. Yamagata (2007). "Impacts of recent El Nino Modoki on dry/wet condidions in the Pacific rim during boreal summer". Clim. Dyn. 29 (2–3): 113–129. Bibcode:2007ClDy...29..113W. doi:10.1007/s00382-007-0234-0 (inactive 2015-01-12).
- Ashok, K., and T. Yamagata (2009). "The El Nino with a difference" 461 (7263). Nature. pp. 481–484.
- Michele Marra (2002-01-01). Modern Japanese Aesthetics: A Reader. University of Hawaii Press. ISBN 978-0-8248-2077-0.
- Johnson, Nathaniel C. (2013). "How Many ENSO Flavors Can We Distinguish?". J. Climate 26 (13): 4816–27. Bibcode:2013JCli...26.4816J. doi:10.1175/JCLI-D-12-00649.1.
- Hye-Mi Kim; Peter J. Webster; Judith A. Curry (2009). "Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones". Science 335 (5936): 77–80. Bibcode:2009Sci...325...77K. doi:10.1126/science.1174062.
- Yeh, Sang-Wook; Kug, Jong-Seong; Dewitte, Boris; Kwon, Min-Ho; Kirtman, Ben P.; Jin, Fei-Fei (September 2009). "El Niño in a changing climate". Nature 461 (7263): 511–4. Bibcode:2009Natur.461..511Y. doi:10.1038/nature08316. PMID 19779449.
- Collins, M.; An, S-I; Cai, W.; Ganachaud, A.; Guilyardi, E.; Jin, F-F; Jochum, M.; Lengaigne, M.; Power, S.; Timmermann, A.; Vecchi, G.; Wittenberg, A. (2010). "The impact of global warming on the tropical Pacific Ocean and El Niño". Nature Geosci. 3 (6): 391–7. Bibcode:2010NatGe...3..391C. doi:10.1038/ngeo868.
- Nicholls, N. (2008). "Recent trends in the seasonal and temporal behaviour of the El Niño Southern Oscillation". Geophys. Res. Lett. 35 (19): L19703. Bibcode:2008GeoRL..3519703N. doi:10.1029/2008GL034499.
- McPhaden, M.J.; Lee, T.; McClurg, D. (2011). "El Niño and its relationship to changing background conditions in the tropical Pacific Ocean". Geophys. Res. Lett. 38 (15): L15709. Bibcode:2011GeoRL..3815709M. doi:10.1029/2011GL048275.
- Giese, B.S.; Ray, S. (2011). "El Niño variability in simple ocean data assimilation (SODA), 1871–2008". J. Geophys. Res. 116: C02024. Bibcode:2011JGRC..116.2024G. doi:10.1029/2010JC006695.
- Newman, M.; Shin, S.-I.; Alexander, M.A. (2011). "Natural variation in ENSO flavors". Geophys. Res. Lett. 38 (14): L14705. Bibcode:2011GeoRL..3814705N. doi:10.1029/2011GL047658.
- Yeh, S.‐W.; Kirtman, B.P.; Kug, J.‐S.; Park, W.; Latif, M. (2011). "Natural variability of the central Pacific El Niño event on multi‐centennial timescales". Geophys. Res. Lett. 38 (2): L02704. Bibcode:2011GeoRL..38.2704Y. doi:10.1029/2010GL045886.
- Hanna Na; Bong-Geun Jang; Won-Moon Choi; Kwang-Yul Kim (2011). "Statistical simulations of the future 50-year statistics of cold-tongue El Niño and warm-pool El Niño". Asia-Pacific J. Atmos. Sci. 47 (3): 223–233. Bibcode:2011APJAS..47..223N. doi:10.1007/s13143-011-0011-1.
- L'Heureux, M.; Collins, D.; Hu, Z.-Z. (2012). "Linear trends in sea surface temperature of the tropical Pacific Ocean and implications for the El Niño-Southern Oscillation". Climate Dynamics 40 (5–6): 1–14. Bibcode:2013ClDy...40.1223L. doi:10.1007/s00382-012-1331-2.
- Lengaigne, M.; Vecchi, G. (2010). "Contrasting the termination of moderate and extreme El Niño events in coupled general circulation models". Climate Dynamics 35 (2–3): 299–313. Bibcode:2010ClDy...35..299L. doi:10.1007/s00382-009-0562-3.
- Takahashi, K.; Montecinos, A.; Goubanova, K.; Dewitte, B. (2011). "ENSO regimes: Reinterpreting the canonical and Modoki El Niño". Geophys. Res. Lett. 38 (10): L10704. Bibcode:2011GeoRL..3810704T. doi:10.1029/2011GL047364.
- S. George Philander (2004). Our Affair with El Niño: How We Transformed an Enchanting Peruvian Current Into a Global Climate Hazard. ISBN 978-0-691-11335-7.
- "Study Finds El Ninos are Growing Stronger". NASA. Retrieved August 3, 2014.
- "Reinterpreting the Canonical and Modoki El Nino". Wiley Online Library. doi:10.1029/2011GL047364. Retrieved August 3, 2014.
- Different Impacts of Various El Niño Events (PDF) (Report). NOAA.
- Central Pacific El Nino on US Winters (Report). IOP Science. Retrieved August 3, 2014.
- "El Niño and its health impact". Health Topics A to Z. Retrieved 2011-01-01.
- Ballester, Joan; Jane C. Burns; Dan Cayan; Yosikazu Nakamura; Ritei Uehara; Xavier Rodó (2013). "Kawasaki disease and ENSO-driven wind circulation". Geophysical Research Letters 40 (10): 2284–2289. Bibcode:2013GeoRL..40.2284B. doi:10.1002/grl.50388.
- Rodó, Xavier; Joan Ballester; Dan Cayan; Marian E. Melish; Yoshikazu Nakamura; Ritei Uehara; Jane C. Burns (2011-11-10). "Association of Kawasaki disease with tropospheric wind patterns". Scientific Reports 1: 152. Bibcode:2011NatSR...1E.152R. doi:10.1038/srep00152. ISSN 2045-2322. PMC 3240972. PMID 22355668.
- Hsiang, S. M. , Meng, K. C. & Cane, M. A.; Meng; Cane (2011). "Civil conflicts are associated with the global climate". Nature 476 (7361): 438–441. Bibcode:2011Natur.476..438H. doi:10.1038/nature10311. PMID 21866157.
- Quirin Schiermeier (2011). "Climate cycles drive civil war". Nature 476 (7361): 406–407. doi:10.1038/news.2011.501. PMID 21866150.
- Carrè, Matthieu et al. (2005). "Strong El Niño events during the early Holocene: stable isotope evidence from Peruvian sea shells". The Holocene 15 (1): 42–7. doi:10.1191/0959683605h1782rp.
- "El Nino here to stay". BBC News. Retrieved 2010-05-01.
- Brian Fagan (1999). Floods, Famines and Emporers: El Niño and the Fate of Civilizations. Basic Books. pp. 119–138. ISBN 0-465-01120-9.
- Grove, Richard H. (1998). "Global Impact of the 1789–93 El Niño". Nature 393 (6683): 318–9. Bibcode:1998Natur.393..318G. doi:10.1038/30636.
- Ó Gráda, C. (2009). "Ch. 1: The Third Horseman". Famine: A Short History. Princeton University Press. ISBN 9780691147970.
- Dimensions of need – People and populations at risk. Food and Agriculture Organization of the United Nations (FAO).
- Trenberth, Kevin E.; Hoar, Timothy J. (1996). "The 1990–1995 El Niño–Southern Oscillation Event: Longest on Record". Geophysical Research Letters 23 (1): 57–60. Bibcode:1996GeoRL..23...57T. doi:10.1029/95GL03602 (inactive 2015-01-12).
- Trenberth, K. E. et al. (2002). "Evolution of El Niño – Southern Oscillation and global atmospheric surface temperatures". Journal of Geophysical Research 107 (D8): 4065. Bibcode:2002JGRD..107.4065T. doi:10.1029/2000JD000298 (inactive 2015-01-12).
- Marshall, Paul; Schuttenberg, Heidi (2006). A reef manager's guide to coral bleaching. Townsville, Qld.: Great Barrier Reef Marine Park Authority. ISBN 1-876945-40-0.
- ENSO Cycle: Recent Evolution, Current Status and Predictions. National Weather Service, Climate Prediction Center.
- K. Yamasaki, A. Gozolchiani, S. Havlin; De Arcangelis, L.; Godano, C. (2008). "Climate networks around the globe are significantly affected by El Nino". Phys. Rev. Lett 100 (3): 228501. arXiv:0709.1792. Bibcode:2008PhRvL.100c8501L. doi:10.1103/PhysRevLett.100.038501.
- Kuenzer, C.; Zhao, D.; Scipal, K.; Sabel, D.; Naeimi, V.; Bartalis, Z.; Hasenauer, S.; Mehl, H.; Dech, S.; Waganer, W. (2009). "El Niño southern oscillation influences represented in ERS scatterometer-derived soil moisture data". Applied Geography 29 (4): 463–477. doi:10.1016/j.apgeog.2009.04.004.
- Caviedes, César N. (2001). El Niño in History: Storming Through the Ages. Gainesville: University of Florida Press. ISBN 0-8130-2099-9.
- Fagan, Brian M. (1999). Floods, Famines, and Emperors: El Niño and the Fate of Civilizations. New York: Basic Books. ISBN 0-7126-6478-5.
- Glantz, Michael H. (2001). Currents of change. Cambridge: Cambridge University Press. ISBN 0-521-78672-X.
- Philander, S. George (1990). El Niño, La Niña and the Southern Oscillation. San Diego: Academic Press. ISBN 0-12-553235-0.
- Trenberth, Kevin E. (1997). "The definition of El Niño" (PDF). Bulletin of the American Meteorological Society 78 (12): 2771–7. Bibcode:1997BAMS...78.2771T. doi:10.1175/1520-0477(1997)078<2771:TDOENO>2.0.CO;2. ISSN 1520-0477.
- Kuenzer, C.; Zhao, D.; Scipal, K.; Sabel, D.; Naeimi, V.; Bartalis, Z.; Hasenauer, S.; Mehl, H.; Dech, S.; Waganer, W. (2009). "El Niño southern oscillation influences represented in ERS scatterometer-derived soil moisture data". Applied Geography 29 (4): 463–477. doi:10.1016/j.apgeog.2009.04.004.
- Li, J.; Xie, S.-P.; Cook, E.R.; Morales, M.; Christie, D.; Johnson, N.; Chen, F.; d’Arrigo, R.; Fowler, A.; Gou, X.; Fang, K. (2013). "El Niño modulations over the past seven centuries". Nature Climate Change 3 (9): 822–826. Bibcode:2013NatCC...3..822L. doi:10.1038/nclimate1936.
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