How often does El Nino occur?
El Niño is one of the most important weather-producing phenomena on Earth. The changing ocean conditions disrupt weather patterns and marine life in the Pacific and around the world. Satellites are unraveling the many traits of this wild child of weather.
How does El Niño affect the Pacific Ocean?
The term El Niño (Spanish for 'the Christ Child') refers to a warming of the ocean surface, or above-average sea surface temperatures, in the central and eastern tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other direction (from west to east …
Who tracks and studies El Niño?
Feb 02, 2016 · El Niño occurs on average every two to seven years, and episodes typically last nine to 12 months. El Nino has its largest impacts during the winter. In the winter, El Niño typically brings milder weather to the northern parts of the United States and wetter conditions across the southern United States.
How do scientists predict El Nino?
El Niño events of 1982-83 and 1997-98 were the most intense of the 20th century. During the 1982-83 event, sea surface temperatures in the eastern tropical Pacific were 9 …
What were the conditions that led to the Spanish conquest of the Incas and Peru?
Historical research has suggested that the Spanish conquest of the Incas and Peru may have been aided by El Niño conditions. When Francisco Pizarro first sailed from Panama along the west coast of South America in 1524, his progress was slowed and ultimately stopped by persistent south and southeasterly winds—which follow the pattern of the north-flowing coastal currents. In 1525-26, however, Pizarro got much farther down the coast, riding on favorable northeasterly winds, according to geographer Cesar Caviedes, author of El Niño in History.
What is the Southern Oscillation?
While working as Director of Observatories in India and studying the monsoon, Gilbert Walker noted that "when pressure is high in the Pacific Ocean it tends to be low in the Indian Ocean from Africa to Australia; these conditions are associated with low temperatures in both these areas, and rainfall varies in the opposite direction to pressure." He dubbed the alternating atmospheric weather pattern the " Southern Oscillation ," noting how highs over the tropical Pacific coincided with lows over the Indian Ocean, and vice versa.
Who was Jacob Bjerknes?
It would be another four decades before Jacob Bjerknes—a Norwegian-born scientist who helped found the meteorology department at the University of California, Los Angeles—made the final connection between the alternating warm and cool patterns in Pacific waters and the atmospheric circulation described by Walker.
What is the Southern Oscillation?
The Southern Oscillationis a change in air pressure over the tropical Pacific Ocean. When coastal waters become warmer in the eastern tropical Pacific (El Niño), the atmospheric pressureabove the ocean decreases. Climatologists define these linked phenomena as El Niño-Southern Oscillation (ENSO).
Where are buoys located?
The buoys are located at about 70 locations in the southern Pacific Ocean, from the Galapagos Islands to Australia.
What is the process of upwelling?
The westward movement of warmer waters causes cooler waters to rise up towards the surface on the coasts of Ecuador, Peru, and Chile. This process is known as upwelling. Upwelling elevates cold, nutrient-rich water to the euphotic zone, the upper layer of the ocean.
What is upwelling in fisheries?
Upwelling provides food for a wide variety of marine life, including most major fisheries . Fishing is one of the primaryindustries of Peru, Ecuador, and Chile. Some of the fisheries include anchovy, sardine, mackerel, shrimp, tuna, and hake. The upwelling process also influences global climate.
What is the global circulation?
Global atmospheric circulationis the large-scale movement of air that helps distribute thermal energy(heat) across the surface of the Earth. The eastward movement of oceanic and atmospheric heat sources cause unusually severe winter weather at the higher latitudes of North and South America.
What is the NOAA?
National Oceanic and Atmospheric Administration (NOAA) noun. U.S. Department of Commerce agency whose mission is to "understand and predict changes in climate, weather, oceans, and coasts; to share that knowledge and information with others, and; to conserve and manage coastal and marine ecosystems and resources.".
What is the definition of a coast?
coast. noun. edge of land along the sea or other large body of water. convection. noun. transfer of heat by the movement of the heated parts of a liquid or gas. crop.
What countries are affected by El Nino?
The fishing industry is also affected. Drought caused by El Nino can be widespread, affecting southern Africa, India, Southeast Asia, Australia, and the Pacific Islands. Countries dependent on agriculture are affected. Australia and Southeast Asia get hotter.
Where does ENSO occur?
As the name suggests, it is an irregular periodic variation of wind and sea surface temperature that occurs over the tropical eastern Pacific Ocean. ENSO affects the tropics (the regions surrounding the equator) and the subtropics (the regions adjacent to or bordering the tropics).
Effects
Episodic shifts in winds and water currents across the equatorial Pacific can cause floods in the South American desert while stalling and drying up the monsoon in Indonesia and India. Atmospheric circulation patterns that promote hurricanes and typhoons in the Pacific can also knock them down over the Atlantic. Fish populations in one part of the ocean might crash, while …
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Climate
The circulation of the air above the tropical Pacific Ocean responds to this tremendous redistribution of ocean heat. The typically strong high-pressure systems of the eastern Pacific weaken, thus changing the balance of atmospheric pressure across the eastern, central, and western Pacific. While easterly winds tend to be dry and steady, Pacific westerlies tend to come …
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Causes
Because of the vastness of the Pacific basincovering one-third of the planetthese wind and humidity changes get transmitted around the world, disrupting circulation patterns such as jet streams (strong upper-level winds). We know these large-scale shifts in Pacific winds and waters initiate El Niño. What we don't know is what triggers the shift. This remains a scientific mystery. I…
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Research
NASA, the National Oceanic and Atmospheric Administration (NOAA), and other scientific institutions track and study El Niño in many ways. From underwater floats that measure conditions in the depths of the Pacific to satellites that observe sea surface heights and the winds high above it, scientists now have many tools to dissect this l'enfant terrible of weather. The dat…
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Physical characteristics
The ocean is not uniform. Temperatures, salinity, and other characteristics vary in three dimensions, from north to south, east to west, and from the surface to the depths. With its own forms of underwater weather, the seas have fronts and circulation patterns that move heat and nutrients around ocean basins. Changes near the surface often start with changes in the depths.
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Introduction
But as an El Niño pattern develops and trade winds weaken, gravity causes the warm water to move east. This mass, referred to as the \"western Pacific warm pool,\" extends down to about 200 meters in depth, a phenomenon that can be observed by moored or floating instruments in the ocean: satellite-tracked drifting buoys, moorings, gliders, and Argo floats that cycle from the …
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Results
The maps above show sea surface temperature anomalies in the Pacific from winter and fall of 2015. The maps do not depict absolute temperatures; instead, they show how much above (red) or below (blue) the surface water temperatures were compared to a long-term (30-year) average. The maps were built with data from a multi-satellite analysis assembled by researchers from NO…
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Habitat
Sea level is naturally higher in the western Pacific; in fact, it is normally about 40 to 50 centimeters (15-20 inches) higher near Indonesia than off of Ecuador. Some of this difference is due to tropical trade winds, which predominantly blow from east to west across the Pacific Ocean, piling up water near Asia and Oceania. Some of it is also due to the heat stored in the water, so measu…
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Analysis
The animation above compares sea surface heights in the Pacific Ocean as measured by the altimeter on the OSTM/Jason-2 satellite and analyzed by scientists at NASAs Jet Propulsion Laboratory. It shows sea surface height anomalies, or how much the water stood above or below its normal sea level. Shades of red indicate where the ocean was higher because warmer water …
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Mechanism
As you watch sea surface heights change through 2015, note the pulses of warmer water moving east across the ocean. When the trade winds ease and bursts of wind come out of the west, warm water from the western Pacific pulses east in vast, deep waves (Kelvin waves) that even out sea level a bit. As the warm water piles up in the east, it deepens the warm surface layer, lowering th…
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Diet
Historic observations have shown that with less phytoplankton available, the fish that feed upon planktonand the bigger fish that feed on the little oneshave a greatly reduced food supply. In most extreme El Niños, the decline in fish stocks has led to famine and dramatic population declines for marine animals such as Galapagos penguins, marine iguanas, sea lions, and seals.
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Behavior
The behavior of the winds and waters are tightly intertwined in the Pacific basin during an El Niño event. \"It is like the proverbial chicken-and-egg problem,\" says Michael McPhaden of NOAAs Pacific Marine Environmental Laboratory. During an El Niño year, weakening winds along the equator lead to warming water surface temperatures that lead to further weakening of the winds.
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Usage
The image below shows the dominant direction of the winds and changes in their intensity near the ocean surface as observed by NASAs RapidScat instrument. Arrows show how the primary wind direction changed from January 2015 to January 2016. The change in wind speed is represented by colors, with surface wind speeds increasing in teal-green areas and decreasing i…
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Appearance
The globes show cloud fraction over the Pacific Ocean in January and November 2015 as measured by the MODIS instrument on NASA's Aqua satellite. The data show how often and how much the sky was filled with clouds over a particular region. Cloudiness is a result of moisture rising from the ocean surface into the atmosphere. During an El Niño (November image), cloud c…
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Origin
El Niño was identified and named long before science caught up with the phenomenon. For centuries, Peruvian fishermen reaped a bounty off the Pacific coast of South America, where north- and west-flowing currents pulled cool, nutrient-rich water from the deep. But every so often, the currents would stop or turn around; warm water from the tropics would drive the fish away a…
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Prelude
When Pizarro returned in 1531-32, his ships made haste down the coast, pushed along again by strong northeasterliesthe kind that blow in El Niño years. Once Spanish troops moved inland, they found blooming deserts, swollen rivers, and rainfall in the usually arid regions of Peru and Ecuador. The humid air and moist land allowed the conquistadors to sustain their long march an…
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Purpose
\"To ask why El Niño occurs is like asking why a bell rings or a pendulum swings,\" atmospheric scientist George Philander wrote in a 1999 paper. \"It is a natural mode of oscillation. A bell, of course, needs to be struck in order to ring.\" After nearly 100 years of investigation, scientists are still not sure what rings the bell; they just know that it rings.
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Events
Fires raging in Indonesia. Fisheries collapsing off Peru. Delayed monsoon rains over India. Floods and mosquito-borne disease outbreaks in South America. Epic drought and mass migrations in southern Africa. Once an El Niño is declared, it seems every extreme weather-related event in the world is blamed on this phenomenon.
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Significance
El Niño is the largest natural disruption to the Earth system, with direct impacts across most of the Pacific Ocean. Indirect impacts reverberate around the globe in patterns that scientists refer to as \"teleconnections.\" Scientists are actively trying to understand how these changes in weather patterns in one area can alter the movement of air masses and winds in areas adjacent …
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Discovery
Subtle changes in the color of the oceanwhich indicate shifts in the abundance and location of the phytoplankton (visible via the pigment chlorophyll-a)were first observed from space by the Coastal Zone Color Scanner in the 1970s and 80s. In fact, imagery collected by CZCS during the very strong 1982-83 El Niño showed the regional demise of marine life around the Galapagos Isl…
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