8. El Niño


8. El Niño

Non-chronological links:

NOAA's El Niño & La Niña web page - https://www.climate.gov/enso

Air-Sea Interactions - 15 multimedia resources from Teachers' Domain Earth and Space Science multimedia resources (movies and interactives).

El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued by Climate Prediction Center/NCEP 

Reverberations of the Pacific Warm Pool - El Niño-like climate anomalies. E.g. the Indo-Pacific warm pool spanning western waters of the equatorial Pacific to the eastern Indian Ocean, holding the warmest seawaters in the world. Over decades, average annual temperatures increase and then decrease like a beacon, may affect climate in regions as far away as  southern United States, and may be powerful enough to broaden the extent of El Niño.

Sea Level Viewer interactive tool at NASA's "Ocean Surface Topography from Space" Web site.


OceanWorld - An ocean-science web site  by Texas A&M Universitywith info about ocean processes, links to teaching material and sources of real-time data. Also complete college-level and graduate courses in oceanography and physical oceanography.

NASA's Aqua Mission Aqua focuses on the multi-disciplinary study of Earth's interrelated processes (atmosphere, oceans, and land surface) and their relationship to changes in the Earth system. Data sets include atmospheric temperature and humidity profiles, clouds, precipitation and radiative balance; terrestrial snow and sea ice; sea surface temperature and ocean productivity; soil moisture. 

NASA Ocean Currents animation.

USGS site (http://ga.water.usgs.gov/edu/) -- Earth water chart

ForgeFX Interactive 3D simulation by Prentice Hall - OCEAN WAVES - demonstrates the connection between wind speed and ocean particle motion depth.

Weather Topics -- From USA Today: climate change, El Niño/La Niña, ocean weather, hurricanes, snow & ice, weather satellites, and global weather patterns. Email weather-related questions to USA Today's weather page editor, Jack Williams.

Articles from 1998–present

2021-05-20. [https://eos.org/articles/your-summer-outlook-cloudy-with-an-above-normal-chance-of-hurricanes] - Your Summer Outlook: Cloudy with an Above-Normal Chance of Hurricanes. Source: By Jenessa Duncombe, Eos/AGU. Excerpt: This year may be the sixth consecutive above-normal Atlantic hurricane season. NOAA released its season outlook today and predicted that it will be another doozy in the Atlantic. ...“Climate change has not been directly linked to the frequency of named tropical storms, but it has been linked to an increase in the intensity of storms,” said Rosencrans. The reason for the higher number of storms this year comes from the ongoing periodic climate fluctuation called the Atlantic Multidecadal Oscillation. We have been in a warm phase since 1995, leading to more storms. ...The storm season could be on the more extreme end of the outlook if another large climate phenomenon, the El Niño–Southern Oscillation (ENSO), switches to its La Niña phase. ...Last year was a record-setting year for hurricanes. We had 30 named storms, surpassing the previous record of 28 in 2005.... 

2020-10-16. Distant seas might predict Colorado River droughts. By Warren Cornwall, Science Magazine. Excerpt: ...scientists say they may have come up with a potential early warning system for the Colorado’s water levels—by watching temperature patterns in the Atlantic and Pacific oceans, thousands of kilometers away. ...Scientists have long recognized links between ocean temperatures and continental weather patterns. Most famously, the central Pacific’s El Niño—a periodic warming of ocean waters—has been tied to drought in Africa, torrential rains on the Pacific coast of North America, and wildfires in South America. ...The scientists found that in the seven most extreme drought years over the past 6 decades, including 2012, the downturn nearly always happened on the heels of a multiyear pattern of global ocean temperatures, they report this month in Communications Earth & Environment. Those patterns started with unusual warm spells in the tropical Atlantic 3 to 4 years before the drought, and continued with warming in the northern Pacific and cooling in the central Pacific 1 to 2 years before the drought.... [https://www.sciencemag.org/news/2020/10/distant-seas-might-predict-colorado-river-droughts

2020-09-10. September 2020 ENSO update: La Niña is here! By: Emily Becker, NOAA. Excerpt: La Niña conditions were present in August, and there’s a 75% chance they’ll hang around through the winter. NOAA has issued a La Niña Advisory. ...La Niña’s altered atmospheric circulation over the Pacific Ocean affects global weather and climate. ...La Niña can make certain outcomes more likely. This includes more rain than average through Indonesia, cooler and wetter weather in southern Africa, and drier weather in southeastern China, among other impacts. ...One important global impact of La Niña is its effect on the Atlantic hurricane season. La Niña reduces wind shear—the change in winds between the surface and the upper levels of the atmosphere—allowing hurricanes to grow. The likelihood of La Niña was factored into NOAA’s August outlook for the Atlantic hurricane season, which favored an “extremely active” season. As of September 8th, we have seen 17 named storms so far this season, and the forecast is for a total of 19-25 named storms (the hurricane season ends on Nov. 30th).... [https://www.climate.gov/news-features/blogs/enso/september-2020-enso-update-la-niña-here]  

2019-12-31. A warning from ancient tree rings: The Americas are prone to catastrophic, simultaneous droughts. By Paul Voosen, Science Magazine. 

2019-04-02. North Atlantic Circulation Patterns Reveal Seas of Change. By Mary Caperton Morton, Eos/AGU.

2018-03-08. Fleet of sailboat drones could monitor climate change’s effect on oceans. By Paul Voosen, Science. 

2016-12-27. Notorious Ocean Current Is Far Stronger Than Previously Thought. By Emily Underwood, EoS Earth & Space news, AGU. 

2016-02-01. Studying the Heart of El Niño, Where Its Weather Begins. By Henry Fountain, The New York Times.

2015-12-15. NASA Examines Global Impacts of the 2015 El Niño. By NASA Release 15-235.

2015-06-17. Mysterious Warm Blob in Pacific Wreaking Havoc. By Patrick J. Kiger, D news.

2008 May 1. Next decade 'may see no warming'. By Richard Black, Environment correspondent, BBC News website. The Earth's temperature may stay roughly the same for a decade, as natural climate cycles enter a cooling phase, scientists have predicted. A new computer model developed by German researchers, reported in the journal Nature, suggests the cooling will counter greenhouse warming. However, temperatures will again be rising quickly by about 2020, they say.
Other climate scientists have welcomed the research, saying it may help societies plan better for the future.
...The key to the new prediction is the natural cycle of ocean temperatures called the Atlantic Multidecadal Oscillation (AMO), which is closely related to the warm currents that bring heat from the tropics to the shores of Europe.
The cause of the oscillation is not well understood, but the cycle appears to come round about every 60 to 70 years.
..."One message from our study is that in the short term, you can see changes in the global mean temperature that you might not expect given the reports of the Intergovernmental Panel on Climate Change (IPCC)," said Noel Keenlyside from the Leibniz Institute of Marine Sciences at Kiel University.
His group's projection diverges from other computer models only for about 15-20 years; after that, the curves come back together and temperatures rise.
...Modelling of climatic events in the oceans is difficult, simply because there is relatively little data on some of the key processes, such as the meridional overturning circulation (MOC) - sometimes erroneously known as the Gulf Stream - which carries heat northwards in the Atlantic.
...Looking forward, the model projects a weakening of the MOC and a resulting cooling of north Atlantic waters, which will act to keep temperatures in check around the world, much as the warming and cooling associated with El Nino and La Nina in the Pacific bring global consequences....

2008 Mar 1. HEAVY RAIN FLOODS SOUTH AMERICA. NASA Earth Observatory News. Persistent, heavier-than-normal rains throughout February and March 2008 triggered flooding across parts of northern and central South America. La Niña conditions in the Pacific may have caused the unusual rainfall.

2008 April 4. Global temperatures 'to decrease'. By Roger Harrabin, BBC News environment analyst. Excerpt: La Niña caused some of the coldest temperatures in memory in China. Global temperatures this year will be lower than in 2007 due to the cooling effect of the La Niña current in the Pacific, UN meteorologists have said. The World Meteorological Organisation's secretary-general, Michel Jarraud, told the BBC it was likely that La Nina would continue into the summer. This would mean global temperatures have not risen since 1998, prompting some to question climate change theory. But experts have also forecast a record high temperature within five years. 'Variability'
La Niña and El Niño are two great natural Pacific currents whose effects are so huge they resonate round the world. El Niño warms the planet when it happens, La Niña cools it. This year, the Pacific is in the grip of a powerful La Niña. It has contributed to torrential rains in Australia and to some of the coldest temperatures in memory in snow-bound parts of China.
Refers to the extensive cooling of the central and eastern Pacific ...Increased sea temperatures on the western side of the Pacific means the atmosphere has more energy and frequency of heavy rain and thunderstorms is increased. ....Typically lasts for up to 12 months and generally less damaging event than the stronger El Niño.

2008 January 10. NASA Observes La Niña: This 'Little Girl' Makes a Big Impression Excerpt: Cool, wet conditions in the Northwest, frigid weather on the Plains, and record dry conditions in the Southeast, all signs that La Niña is in full swing. With winter gearing up, a moderate La Niña is hitting its peak. And we are just beginning to see the full effects of this oceanographic phenomenon, as La Niña episodes are typically strongest in January. A La Niña event occurs when cooler than normal sea surface temperatures form along the equator in the Pacific Ocean, specifically in the eastern to central Pacific. The La Niña we are experiencing now has a significant presence in the eastern part of the ocean. The cooler water temperatures associated with La Niña are caused by an increase in easterly sea surface winds. Under normal conditions these winds force cooler water from below up to the surface of the ocean. When the winds increase in speed, more cold water from below is forced up, cooling the ocean surface. "With this La Niña, the sea-surface temperatures are about two degrees colder than normal in the eastern Pacific and that's a pretty significant difference," says David Adamec of NASA's Goddard Space Flight Center, Greenbelt, Md. "I know it doesn't sound like much, but remember this is water that probably covers an area the size of the United States. It's like you put this big air conditioner out there - and the atmosphere is going to feel it." While this "air conditioner" may be located in the equatorial Pacific Ocean, it has a great influence on the weather here in the United States and across the globe. ...The Northwest generally experiences cooler, wetter weather during a La Niña. On the Great Plains, residents normally see a colder than normal winter and southeastern states traditionally experience below average rainfall. ...The increased circulation that brings up cold water from below also brings up with it nutrients from the deeper waters. These nutrients feed the organisms at the bottom of the food chain, starting a reaction that increases life in the ocean. NASA's SeaWiFS satellite documented this increase in hytoplankton during the last La Niña period in 1998. La Niña and El Niño episodes tend to occur every three to five years. La Niñas are often preceded by an El Niño, however this cycle is not guaranteed. The lengths of La Niña events vary as well. "We need to watch to see if this La Niña diminishes, because they can last for multiple years....

2006 September 23. Nature provides "ecosystem services". Earth & Sky Radio Show.

2006 September 19. El Nino mystery solved, monsoon forecasts improved. Earth & Sky Radio Show.


1 December 2005. Alarm over dramatic weakening of Gulf Stream. Ian Sample, science correspondent, The Guardian Excerpt: Slowing of current by a third in 12 years could bring more extreme weather. Temperatures in Britain likely to drop by one degree in next decade. The powerful ocean current that bathes Britain and northern Europe in warm waters from the tropics has weakened dramatically in recent years, a consequence of global warming that could trigger more severe winters and cooler summers across the region, scientists warn today. Researchers on a scientific expedition in the Atlantic Ocean measured the strength of the current between Africa and the east coast of America and found that the circulation has slowed by 30% since a previous expedition 12 years ago. The current, which drives the Gulf Stream, delivers the equivalent of 1m power stations-worth of energy to northern Europe, propping up temperatures by 10C in some regions. ... Previous expeditions to check the current flow in 1957, 1981 and 1992 found only minor changes in its strength, although a slowing was picked up in a further expedition in 1998.... If the current remains as weak as it is, temperatures in Britain are likely to drop by an average of 1C in the next decade, according to Harry Bryden at the National Oceanography Centre in Southampton who led the study. ...The current is essentially a huge oceanic conveyor belt that transports heat from equatorial regions towards the Arctic circle. Warm surface water coming up from the tropics gives off heat as it moves north until eventually, it cools so much in northern waters that it sinks and circulates back to the south. There it warms again, rises and heads back north. The constant sinking in the north and rising in the south drives the conveyor. Global warming weakens the circulation because increased meltwater from Greenland and the Arctic icesheets along with greater river run-off from Russia pour into the northern Atlantic and make it less saline which in turn makes it harder for the cooler water to sink, in effect slowing down the engine that drives the current....


1 December 2004. NASA SATELLITES WITNESSED EL NIÑO CREEP IN FROM THE INDIAN OCEAN. NASA Earth Observatory News. El Niño has fascinated people for centuries, and continues to interest people around the world, because it changes global weather patterns....Just in time for this Christmas, an index created to see the development of El Niño events received the approval of the scientific community. Scott Curtis, a NASA-funded scientist from East Carolina University in Greenville, N.C. and colleagues, created an index using satellite data of rain and winds in the eastern Indian Ocean that accurately predicted the arrival of the 2002-2003 El Niño. ... Curtis ... and Robert Adler, George Huffman and Guojun Gu, all of NASA's Goddard Space Flight Center, Greenbelt, Md. used NASA's Tropical Rainfall Measuring Mission (TRMM) and QuikScat satellite data ranging from November 2001 to March 2002. ...The researchers developed the El Niño Onset Index (EOI) using the rainfall data alone. "Because the rainfall data has been a consistent indicator of an on-coming El Niño, as compared to the wind data, only the rainfall data was used to construct the EOI,"

8 November 2004. NASA RELEASE: 04-369. TRMM Satellite Proves El Niño Holds the Reins on Global Rains. NASA scientists recently found the El Niño Southern Oscillation (ENSO) is the main driver of the change in rain patterns all around the world. The NASA and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) satellite has enabled scientists to look around the globe and determine where the year-to-year changes in rainfall are greatest. By studying the rain patterns in these areas over the past 50 years, with rain gauge data prior to 1998, they established the main component of this change in global rainfall is directly correlated with the El Niño Southern Oscillation. The study appeared in a recent issue of the Journal of Geophysical Research-Atmospheres.

15 April 2004. NASA RELEASE: 04-130. SATELLITES RECORD WEAKENING NORTH ATLANTIC CURRENT. A North Atlantic Ocean circulation system weakened considerably in the late 1990s, compared to the 1970s and 1980s, according to a NASA study. Sirpa Hakkinen, lead author and researcher at NASA's Goddard Space Flight Center, Greenbelt, Md. and co-author Peter Rhines, an oceanographer at the University of Washington, Seattle, believe slowing of this ocean current is an indication of dramatic changes in the North Atlantic Ocean climate. The study's results about the system that moves water in a counterclockwise pattern from Ireland to Labrador were published on the Internet by the journal Science on the Science Express Web site at: http://www.sciencexpress.org. The current, known as the sub polar gyre, has weakened in the past in connection with certain phases of a large-scale atmospheric pressure system known as the North Atlantic Oscillation (NAO).

8 March 2004. From science@NASA -- A Chilling Possibility. By disturbing a massive ocean current, melting Arctic sea ice might trigger colder weather in Europe and North America.

5 January 2004. NASA RELEASE: 04-007. EL NINO-RELATED FIRES INCREASE GREENHOUSE GAS EMISSIONS. Year-to-year changes in concentration of carbon dioxide and methane, two important greenhouse gases in the atmosphere, can be linked to fire activity associated with the El Nino-La Nina cycle, according to a study conducted by a team of NASA scientists and other researchers.... Scientists today are trying to understand the relationship between the carbon cycle and the climate system. The carbon cycle is the movement of carbon, in its many forms, among the biosphere, atmosphere, oceans and the geosphere. The cycling of carbon affects the amount of carbon-based greenhouse gases in the atmosphere and thus the Earth's climate. This study shows carbon loss in the biosphere over the next several centuries may be sensitive to the intensity and variability of El Nino-induced droughts.


9 September 2003. El Nino damage in California. NASA's Earth Observatory. In anticipation of the 1997-98 El Niño, the U.S. Federal Emergency Management Agency spent approximately $165 million to prepare for storms and heavy rain in California. Local governments distributed sandbags to residents for flood protection, established volunteer programs to remove debris from storm drains, monitored high flood risk areas, and provided special training to damage-control teams. All of this preparation was possible because the 1997-98 El Niño had been forecast six months in advance.

14 March 2003. A Quirky El Niño. (science@NASA) The 2002-03 El Niño has resisted stereotypes with its unpredictable behavior. ...Sometimes Earth scientist Bill Patzert wishes he had a degree in psychology. It might help him understand El Niño. "Every El Niño has a personality all its own, and the latest one has been very quirky," says Patzert, who works at NASA's Jet Propulsion Laboratory. "Here in southern California we expect El Niño to bring heavy rains. But the weather this winter has had a split-personality, alternating between warm and dry months to very cold and wet months."


1 August 2002. SATELLITES REVEAL A MYSTERY OF LARGE CHANGE IN EARTH'S GRAVITY FIELD -- Satellite data since 1998 indicates the bulge in the Earth's gravity field at the equator is growing, and scientists think that the ocean may hold the answer to the mystery of how the changes in the trend of Earth's gravity are occurring. Goddard Space Flight Center RELEASE: 02-147


11 April 2001. NASA DEMONSTRATES HOW EARTH'S GLOBAL HEAT ENGINE DRIVES PLANT GROWTH. Scientists at NASA GSFC have assembled the first long-term global data set that demonstrates the connection between changing patterns of sea surface temperature and patterns of plant growth across the Earth's landscapes.

6 March 2001. AFTER THREE STRIKES, IS LA NINA OUT? Last Autumn scientists thought La Nina had faded, but recent NASA satellite images revealed La Nina-like conditions lurking in the Pacific for the third year in a row. Will they linger a fourth? Some climate models predict La Nina will vanish in 2001 and that a weak El Nino could take its place. A shift from La Nina to El Nino conditions would likely trigger more rainfall in California where swelling rivers will increase the output of hydroelectric dams, providing the state with some much needed electricity. La Nina-like conditions that have persisted in the Pacific Ocean for three years might finally subside this Fall. The change could pave the way for a weak El Nino -- and a surge of hydroelectricity for power-starved California.

4 January 2001. RAINFALL CHANGE MAY GIVE EARLIER SIGNAL OF EL NINO. A decrease in rainfall over the Indian Ocean may give the world the earliest signal that a strong El Nino is about to start. US Global Change Research Program (USGCRP)


August 1999. El Niño. NASA Earth Science Enterprise Series, Fact Sheet: NF-211 [97KB PDF] El Niño effects are not limited to the disturbed areas off of Peru and Ecuador. They can be transmitted great distances. In many parts of the world, the disruption of normal climate can have tragic and/or profound economic consequences.

June 1999. La Niña. NASA Earth Science Enterprise Series, Fact Sheet: FS-1998-08-017-GSFC [250KB PDF] The coupled atmosphere-ocean phenomenon known as El Niño is frequently followed by a period of normal conditions in the equatorial Pacific Ocean. Sometimes, but not always, El Niño conditions give way to the other extreme of the El Niño-Southern Oscillation (ENSO) cycle. This cold counterpart to El Niño is known as La Niña, Spanish for "the girl child."


February 1998. Using Satellites to Track Rift Valley Fever [200KB PDF NASA Lithograph] Rift Valley Fever (RVF), at least in the African country of Kenya, has been well known for over 60 years. As early as 1913, a disease fitting the description of RVF was blamed for the loss of sheep in the Rift Valley in kenya. However, it was not until scientists studied an outbreak of the disease in 1931 that a virus was isolated and shown to cause the disease. By using satellites to closely monitor the vegetation in the region affected by increased rainfall, scientists can identify likely habitats for the mosquitoes that carry the RVF virus, and provide advance warning of large-scale outbreaks of the disease.

1997-98 El Niño [405KB PDF NASA Lithograph] This image shows the progression of the 1997-98 El Niño as derived from the TOPEX/Poseidon satellite.