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JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
June 19, 2000
These data, taken during a 10-day cycle of collection ending June 9, show that the equatorial Pacific continues to warm up and is returning to normal (green) as this latest, persistent, two- year La Niņa episode is coming to an end. Only a few patches of cooler, lower sea levels (seen in blue and purple) remain across the tropics. It should be noted that in June 1999, La Niņa barely had a pulse, but was resuscitated in fall 1999. (See June 1999 press release on that topic.)
The blue areas are between 5 and 13 centimeters (2 and 5 inches) below normal, whereas the purple areas range from 14 to 18 centimeters (6 to 7 inches) below normal. In the far-western tropical Pacific Ocean, the ocean remains higher and warmer than normal. In summary, it appears that the global climate system is finally emerging from the past three years of dramatic swings from the extra-large El Niņo of 1997/1998, which was followed by two unusually cool and persistent La Niņa years, according to scientists at NASA's Jet Propulsion Laboratory.
But as the northern hemisphere summer begins, above-normal sea surface heights and warmer ocean temperatures (indicated by the red and white areas) still blanket the western equatorial Pacific and much of the north and south mid-Pacific. Red areas are about 10 centimeters (4 inches) above normal; white areas show the sea surface height is between 14 and 32 centimeters (6 to 13 inches) above normal. This contrasts with the Bering Sea and Gulf of Alaska region southward along the western coast of North America, where lower-than-normal sea levels and cool ocean temperatures continue, although this pattern is also weakening. A possible switch in this larger-than-El Niņo/La Niņa, slower- changing pattern -- the Pacific Decadal Oscillation -- was first noticed by many scientists in late 1998. See a January 2000 press release on that topic, or further information and graphics about the Pacific Decadal Oscillation.
"Let's not forget that the legacy of two years of La Niņa will be with us this summer and into the fall, " said JPL oceanographer Dr. William Patzert. "Much of the nation's farmland is really dry in many regions. The reality is that the atmosphere is still acting as though La Niņa remains." The National Oceanic and Atmospheric Administration's (NOAA) National Weather Service has forecasted continuing drought for much of the midwestern and southeastern United States and an active hurricane season for our coming summer. NOAA seasonal forecasts can be found at http://www.cpc.ncep.noaa.gov.
The U.S.-French TOPEX/Poseidon mission is managed by JPL for the NASA's Earth Science Enterprise, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
For more information on the TOPEX/Poseidon project, see http://topex-www.jpl.nasa.gov.
NASA Goddard Space Flight Center
Monterey Bay Aquarium Research Center
National Oceanic and Atmospheric Administration
Dec. 9, 1999
According to new results published in the Dec. 10 issue of the journal Science, El Niņo also dramatically reduced the amount of carbon dioxide normally released into the atmosphere by the equatorial Pacific Ocean.
Data from an array of instruments on buoys, ships and in space, including NASA's Sea-viewing Wide Field-of-View Sensor (SeaWiFS), gave researchers an unprecedented view into the extreme biological effects of this El Niņo/La Niņa event.
"With SeaWiFS in orbit, we were able to see for the first time not only the vast size and intensity of the ocean's biological rebound from El Niņo, but also the unbelievable speed of that recovery," said Goddard Space Flight Center (Greenbelt, Md.) oceanographer Dr. Gene Feldman, a co-author of the study. SeaWiFS provides daily views of the world's oceans and land masses.
Over the past decade scientists have been able to observe the development and progression of El Niņo warmings, and consequent changes in upwelling of nutrient-rich ocean waters, thanks to data continuously collected in the Pacific by the buoys of the National Oceanic and Atmospheric Administration's Tropical Atmosphere Ocean array.
In 1996 new biological and chemical sensors were added to some of these buoys by the Monterey Bay Aquarium Research Institute (MBARI), allowing researchers for the first time to directly and continuously monitor biological productivity and the concentration of carbon dioxide in the region. The launch of SeaWiFS in 1997 added yet another ocean-monitoring tool capable of detecting subtle changes in ocean color that are directly related to the concentration of chlorophyll, a prime indicator of biological activity in ocean waters. The largest reservoir of chlorophyll in the ocean is in the phytoplankton (a microscopic form of algae), which forms the base of the oceanic food chain.
"This is the first time we've ever had a set of biological measurements from moored instruments and satellites during an intense El Niņo, and we've never seen such low chlorophyll concentrations," said MBARI biological oceanographer Francisco Chavez, lead author of the study.
It was the buoy measurements and SeaWiFS data that revealed surprisingly low and then high levels of chlorophyll coinciding with El Niņo's strongest phase and the recovery period and transition to La Nina cooling. When the warm-water layer produced by El Niņo extended to its greatest depths and the upwelling of nutrients necessary for phytoplankton growth virtually ceased, chlorophyll values plummeted.
The researchers were again surprised in mid-1998 when chlorophyll levels skyrocketed, revealing the largest phytoplankton bloom, in area, ever observed in the equatorial Pacific. In their published results, the researchers suggest that elevated iron concentrations stimulated this intense bloom, a result of the increased upwelling associated with La Niņa.
El Niņo also drastically reduced the amount of carbon dioxide this ocean region adds to the atmosphere. Unlike most parts of the world's oceans, the equatorial Pacific is normally a major contributor to atmospheric carbon dioxide due to the carbon-dioxide-rich deep ocean waters brought to the surface here and the relatively low levels of biological activity.
The researchers calculate that the amount of carbon dioxide released to the atmosphere by the equatorial Pacific during the year of El Niņo conditions was 700 million metric tons of carbon less than the previous year. This is equivalent to half of the United States' total annual carbon dioxide emissions from fossil fuel burning.
SeaWiFS images of trhe 1997-98 El Niņo.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
October 20, 1999
TOPEX/Poseidon has detected lower than normal sea-surface heights in the eastern North Pacific and unusually high sea- surface heights in the western and mid-latitude Pacific. The height of the sea surface over a given area is an indicator of ocean temperature and other factors that influence climate.
The latest measurements, taken during a 10-day data cycle October 5-15, are available at http://www.jpl.nasa.gov/elnino. Sea-surface height is shown relative to normal (green) and reveals cooler water (blue and purple) measuring about 14 centimeters (6 inches) lower in the eastern North Pacific, from the Gulf of Alaska to central Alaska, and along the equator. The cooling trend sets the stage for another La Niņa this winter.
A mirror image of that oceanic profile prevails in the western and mid-latitude Pacific Ocean, where higher than normal sea-surface heights (red and white) are currently about 20 centimeters or 8 inches. Unusually warm temperatures (shown in red and white) have persisted and topped last year's temperatures, said Dr. William Patzert, an oceanographer at NASA's Jet Propulsion Laboratory, Pasadena, CA.
"These unbalanced conditions will undoubtedly exert a very strong influence on climate over North America this fall and winter," Patzert said. "Our profile of high sea-surface heights and warm temperatures in the western Pacific Ocean contrasts with low sea-surface heights and cool conditions in the eastern and equatorial Pacific. Those conditions will have a powerful impact on the weather system delivering jet streams out of the North Pacific."
Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California and the Southwest, the data show. "Clearly, these unusual conditions, which have persisted for 2 1/2 years, will not be returning to normal any time soon," Patzert said. "This climate imbalance is big and we're definitely going through a decade of wild climatic behavior. But when we look back at the climate record over the past century, we've seen behavior like this before."
The TOPEX/Poseidon satellite's measurements have provided scientists with a detailed view of the 1997-1999 El Niņo/La Niņa climate pattern by measuring the changing sea-surface height with unprecedented precision.
The U.S./French TOPEX/Poseidon mission is managed by the Jet Propulsion Laboratory for NASA's Office of Earth Sciences, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
June 29, 1999
A new image made from sea-surface height measurements taken by the satellite is available on the Internet. It shows sea-surface height relative to normal ocean conditions (indicated by the green areas) for this time of the year.
The data, taken during a 10-day cycle of data collection ending June 18, show that the equatorial Pacific Ocean is warming up and returning to normal (green) as La Niņa all but vanishes. The warming trend is most apparent in the equatorial Pacific Ocean, where only a few patches of cooler, low sea levels (seen in blue and purple) remain. The blue areas are between 5 and 13 centimeters (2 and 5 inches) below normal, whereas the purple areas range from 14 to 18 centimeters (6 to 7 inches) below normal. Like its counterpart, El Niņo, a La Niņa condition will influence global climate and weather until it has completely subsided.
As summer begins in the northern hemisphere, lower-than- normal sea surface levels and cool ocean temperatures persist in the northeastern Gulf of Alaska and along the western coast of North America. In contrast, the trend is the opposite over most of the Pacific, where above-normal sea surface heights and warmer ocean temperatures (indicated by the red and white areas) appear to be increasing and dominating the overall Pacific Ocean. Red areas are about 10 centimeters (4 inches) above normal; white areas show the sea surface height is between 14 and 32 centimeters (6 and 13 inches) above normal.
Scientists are not ready to administer last rites to La Niņa, though. In the last 12 months, the pool of unusually cold water in the Pacific has shrunk (warmed) several times before cooling (expanding) again. This summer's altimeter data will help them determine whether La Niņa has truly dissipated or whether they will see another resurgence of cool water in the Pacific. The TOPEX/Poseidon mission is managed by the Jet Propulsion Laboratory for NASA's Office of Earth Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
April 22, 1999
New imagery of sea-surface heights taken this month by the ocean-observing satellite show cooler temperatures and lower sea levels across the equatorial Pacific Ocean (seen in blue and purple in the center of the image) are diminishing, which indicates that the equatorial Pacific is slowly returning to normal.
However, in the north and south Pacific Ocean, temperatures and sea level remain high (seen in red and white), a pattern that began many months ago. In a nutshell, this means that although La Nina is fading, heat distribution in the Pacific Ocean remains dramatically out of balance.
The new satellite image is available on the Internet at http://www.jpl.nasa,gov/elnino.
The TOPEX/Poseidon mission is managed by the Jet Propulsion Laboratory for NASA's Office of Earth Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
October 21, 1998
The new image shows that sea level across the tropical Pacific has essentially maintained the same pattern since mid- June 1998. Remnants of the high sea level, warmer El Niņo waters still linger to the north of the equator while the area of low sea level, or cold water that is sometimes referred to as La Niņa, remains in the center of the Pacific. It is still uncertain, scientists say, if the ocean is headed toward a long- lasting La Niņa situation.
The image shows sea-surface height on October 12, 1998, relative to normal ocean conditions. Sea surface height is an indicator of the heat content of the ocean; the pool of cold water in the Pacific is detected by the satellite as a region of lower than normal sea level. The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Niņo, and a possibly waning La Niņa situation. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition. These strong patterns have remained in the climate system for many months and will continue to influence weather conditions around the world in this fall and winter.
A La Niņa is essentially the opposite of an El Niņo condition, but during a La Niņa the trade winds are stronger than normal and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. Like El Niņo, a La Niņa situation also changes global weather patterns, and is associated with less moisture in the air resulting in less rain along the west coasts of North and South America.
The October 12 image is now available online at:
http://www.jpl.nasa.gov/elnino
The U.S.-French TOPEX/Poseidon mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, CA, for NASA's Earth Sciences Enterprise, Washington, DC.
NASA Headquarters, Washington, DC
Goddard Space Flight Center, Greenbelt, MD
July 16, 1998
This temperature data is giving scientists new insight into the complex evolution of the La Niņa event -- the TMI is the only spaceborne microwave instrument observing sea-surface temperature in the tropics. The images show changes in sea-surface temperature, and ocean current movement and the dissipation of El Niņo. While it is too early to draw definite conclusions, the results to date appear to confirm the onset of La Nina type conditions.
"TMI is an all-weather measuring instrument that can see through clouds," said Dr. David Adamec, oceanographer at the Goddard Space Flight Center, Greenbelt, MD. "The standard instrument (infrared radiometer), used to measure sea-surface temperature, must contend with clouds and atmospheric aerosols. Clouds block the flow of data, yet an uninterrupted consistent data stream is crucial for long-term climate study."
La Niņa is essentially the opposite of the El Niņo phenomenon and is characterized by unusually cold ocean temperatures in the equatorial Pacific, as compared to El Niņo, where ocean temperatures are warmer than normal. La Niņa and El Niņo often are spoken of together and termed the El Niņo/Southern Oscillations, or "ENSO." La Nina sometimes is referred to as the cold phase of the ENSO.
At the Earth's surface, La Niņa effects on the world's climate tend to be opposite those of El Niņo. At higher latitudes, El Niņo and La Niņa are just two of several factors that influence climate. However, the impacts of El Niņo and La Niņa at higher latitudes are most clearly seen in winter. During a typical La Niņa year, winter temperatures are warmer than normal in the Southeast and cooler in the Northwest.
Knowledge of La Niņa is not as mature as that for El Niņo. For example, every strong El Niņo is not necessarily followed by a La Niņa. Scientists at Goddard are performing advanced studies of El Niņo and La Niņa through information obtained from satellites in space and instruments in the oceans.
Acquiring quality sea-surface temperature data via a microwave scanner has been a long-term aspiration among oceanographers for more than a decade, when the last microwave imager ceased operations. In addition, none of the previously existing microwave scanners had the capability of the TRMM Microwave Imager. Ideally, this information will be used for the improvement of weather forecasting, anomalous weather study, and a better understanding of ocean current alteration.
Several NASA missions study the effects of El Nino and La Nina with orbiting satellites. The joint U.S.-French TOPEX/Poseidon satellite measures sea surface height; the Sea- Viewing Wide Field-of-View Sensor (SeaWiFS) measures ocean color; and TRMM measures precipitation and sea-surface temperature. The Tropical Atmosphere-Ocean Array consists of nearly 70 moored buoys in the tropical Pacific designed by the National Oceanic and Atmospheric Administration (NOAA). The devices take real-time measurements of air temperature, relative humidity, surface winds, sea surface temperatures and subsurface temperatures down to a depth of 500 meters. Data from these moored buoys is processed by NOAA and then made available to scientists.
The TRMM Microwave Imager instrument was provided by NASA. TRMM was developed jointly by NASA and NASDA and launched last November from NASDA's Tanegashima Space Center, Japan.
This La Niņa research is part of NASA's Earth Science Enterprise, a long-term research program designed to study the Earth's land, oceans, air, ice and life as a total system.
Images on this research are available at URL:
http://www.eorc.nasda.go.jp/TRMM
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
June 26, 1998
"Sea level is a measure of the heat stored in the ocean. In the last month or so, the tropical Pacific has been switching from warm to cold. Lower sea level indicates less heat, hence a colder ocean," said Dr. Lee-Lueng Fu, the project scientist for the U.S.-French TOPEX/Poseidon mission at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "It appears now the central equatorial Pacific Ocean will stay colder than normal for some time to come because sea level is about seven inches below normal, creating a deficit in the heat supply to the surface waters. It is not clear yet, however, if this current cooling trend will eventually evolve into a long-lasting La Niņa situation."
An El Niņo condition begins when steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water that is normally located near Australia to move eastward along the equator until it reaches the coast of South America.
This displaced pool of unusually warm water affects evaporation, where rain clouds form -- and, in turn, alters the typical atmospheric jet stream patterns around the world. The change in the wind strength and direction also impacts global weather patterns. The climatic event has been given the name El Niņo, a Spanish term for "the Christ child," because the warm current first appeared off the coast of South America around Christmas.
The 1997-98 El Niņo has been the strongest ever recorded. This phenomenon was responsible for record rainfall in California, heavy flooding in Peru, drought and wildfires in Indonesia, tornadoes in the southeast United States and loss of life and property damage worldwide. TOPEX/Poseidon's sea surface height measurements have provided scientists with their first detailed view of how El Niņo's warm pool behaves because the satellite measures the changing sea surface height with unprecedented precision.
A "La Niņa" (Spanish for "little girl") is essentially the opposite of an El Niņo, where the trade winds are stronger than normal and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. A La Niņa situation also changes global weather patterns and is associated with less moisture in the air, resulting in less rain along the coasts of North and South America. TOPEX/Poseidon will be able to track a potentially developing La Niņa with the same accuracy.
"It may be too soon to say 'good-bye' El Niņo and 'hello' La Niņa, because the effects of El Niņo will remain in the climate system for a long time," said Dr. Bill Patzert, a research oceanographer at JPL. "However, if the Pacific is transitioning to a La Niņa, we'd expect to see clear, strong indication of it by late summer or early fall -- in approximately August or September -- just like we did last year with El Niņo. The strongest impacts of a potential La Niņa wouldn't be felt in the U.S. until next winter." A La Niņa does not automatically follow an El Niņo, Patzert added.
Developed by NASA and the Centre National d'Etudes Spatiales (CNES), the TOPEX/Poseidon satellite uses an altimeter to bounce radar signals off the ocean's surface to get precise measurements of the distance between the satellite and the sea surface. These data are combined with measurements from other instruments that pinpoint the satellite's exact location in space. Every ten days, scientists produce a complete map of global ocean topography, the barely perceptible hills and valleys found on the sea surface.
Ocean temperatures affect ocean topography, which is why the TOPEX/Poseidon radar altimeter is able to monitor the changing El Niņo and La Niņa conditions. With detailed knowledge of ocean topography, scientists can then calculate the speed and direction of worldwide ocean currents.
The new satellite image from June is available.
JPL, a division of the California Institute of Technology, manages the TOPEX/Poseidon mission for NASA's Earth Science Enterprise, Washington, DC.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
June 2, 1998
Using measurements taken by the NASA Scatterometer (NSCAT) in early 1997, scientists confirmed that an unusual weakening of the trade winds preceded an increase in sea surface temperatures along the central and eastern equatorial Pacific, according to Dr. W. Timothy Liu, the NSCAT project scientist at JPL. "With NSCAT we are able to see the whole El Niņo picture, and we now know that the unusually high ocean temperatures at the equator, along the North American coast and off of Baja, Mexico are all linked together because of the winds," Liu said.
Liu is presented his findings last week at the American Meteorological Society's Conference on Satellite Meteorology and Oceanography in Paris.
An El Niņo condition is thought to be triggered when steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows the large mass of warm water that is normally located near Australia to move eastward along the equator until it reaches the coast of South America.
"The collapse of the trade winds and the depression of the thermocline (cooler water) resulted in an increase of sea surface temperature and sea surface height in early 1997, and this interaction appears to be the typical mechanism of equatorial changes associated with an El Niņo," Liu explained.
In addition to measuring the beginning of El Niņo along the equator, NSCAT also revealed that, when the trade winds weakened, an unusual low-pressure system with cyclonic (counterclockwise) circulation moved toward the North American coast. NSCAT observed that winds branched off from the equator, bypassed Hawaii, and brought heat and moisture from the tropical ocean towards San Francisco via a route often called the "Pineapple Express."
"This moist and warm air from the south kept evaporation low and the ocean water warmer than normal near the North American coast," Liu suggested. "This change brought with it strong ecological changes, such as the tropical fish caught off the coast of Oregon and the deaths of sea lions on the Channel Islands in California."
An image of this "teleconnection" between the warming of equatorial water associated with El Niņo and the warming of the North American coastal waters through wind patterns is available at http://www.jpl.nasa.gov/elnino.
NSCAT was a radar instrument that flew on Japan's Advanced Earth Observing Satellite (ADEOS) until the satellite suffered an electrical failure and ceased functioning on June 30, 1997. JPL is currently building the SeaWinds scatterometer that will fly on the Quick Scatterometer (QuikScat) satellite set for launch in November 1998 will continue the important wind observations begun by NSCAT. SeaWinds will provide better coverage of the ocean than NSCAT and will improve our ability to observe the influence of El Niņo from the equatorial water to regions closer to our home, Liu said.
The scatterometery program is managed by JPL for NASAs Earth Sciences Enterprise, Washington, D.C. JPL is managed for NASA by the California Institute of Technology.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
May 12, 1998
However, conditions in the western equatorial Pacific near Australia have not returned to a normal state and are still well below normal sea level. Oceanographers indicate these measurements show that the Pacific has not yet fully recovered from this large El Niņo event.
The image shows sea-surface height relative to normal ocean conditions on May 3, 1998, and sea-surface height is an indicator of the heat content of the ocean. These sea- surface height measurements have provided scientists with a detailed view of how the 1997-98 El Niņo warm water pool behaves because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision.
Sea surface temperatures, as measured by the National Oceanic and Atmospheric Administration, (NOAA), are still above normal throughout the tropical Pacific Ocean and are expected to remain that way through the spring.
Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, NOAA has extended an advisory indicating that the so-called El Niņo weather conditions that have impacted much of the United States and the world are expected to continue through the spring.
The May 3 image is now available online.
The U.S./French TOPEX/Poseidon mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, CA.
March 20, 1998
The image shows sea surface height relative to normal ocean conditions on Mar.14, 1998 and sea surface height is an indicator of the heat content of the ocean. Oceanographers indicate this is a classic pattern, typical of a mature El Niņo condition that they would expect to see during the ocean's gradual transition back to normal sea level. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Niņo warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision.
Sea surface temperatures, as measured by the National Oceanic and Atmospheric Administration, (NOAA), are still well above normal throughout the tropical Pacific Ocean and are expected to remain that way into April and May.
Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, NOAA has extended an advisory indicating that the so-called El Niņo weather conditions that have impacted much of the United States and the world are expected to continue through the spring.
The Mar. 14 image is now available online at: http://www.jpl.nasa.gov/elnino
The U.S./French TOPEX/Poseidon mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, CA.
February 19, 1998
The image shows sea surface height relative to normal ocean conditions on Feb. 5, 1998 and sea surface height is an indicator of the heat content of the ocean. The area and volume of the El Niņo warm water pool that is affecting global weather patterns remains extremely large, but the pool has thinned along the equator and near the coast of South America. This 'thinning' means that the warm water is not as deep as it was a few months ago. Oceanographers indicate this is a classic pattern, typical of a mature El Niņo condition that they would expect to see during the ocean's gradual transition back to normal sea level.
Sea surface temperatures, as measured by the National Oceanic and Atmospheric Administration, (NOAA), are still well above normal throughout the tropical Pacific Ocean and are expected to remain that way into April and May.
Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, NOAA has continued to issue an advisory indicating the so-called El Niņo weather conditions that have impacted much of the United States and the world are expected to continue through the spring.
The Feb. 5 image is now available online at:
http://www.jpl.nasa.gov/elnino
The U.S./French TOPEX/Poseidon mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology.
December 5, 1997
The image is now available online.
The image was created using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite, managed at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology.
The image shows sea surface height relative to normal ocean conditions on Dec. 1, 1997 as the warm water associated with El Niņo spreads northward along the entire coast of North America from the equator all the way to Alaska. The volume of the warm water related to El Niņo has receded to about the level it was in early September. Oceanographers note that this El Niņo has just completed a classic "double peak" pattern, with the first peak in volume occurring in early October, and the second peak in volume coming in early November. This pattern is very similar to what was observed during the 1982-83 El Niņo.
November 18, 1997
The image is now available online at:
http://www.jpl.nasa.gov/elnino
The image was created using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite, managed at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology.
The image shows sea surface height relative to normal ocean conditions on Nov. 10, 1997 as the warm water associated with El Niņo spreads northward along the entire coast of North America from the equator all the way to Alaska. The volume of extra surface warm water in the core of the El Niņo continues to increase, especially in the area between 15 degrees South latitude and 15 degrees North latitude in the Pacific Ocean.
NASA Headquarters, Washington, DC
Jet Propulsion Laboratory, Pasadena, CA
September 15, 1997
"The new data collected since April 1997 confirm what we had earlier speculated upon and what the National Oceanic and Atmospheric Administration (NOAA) has predicted -- a full-blown El Niņo condition is established in the Pacific," said Dr. Lee-Lueng Fu, project scientist for the U.S./French satellite TOPEX/POSEIDON satellite at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA.
The five years of global ocean topography observations made by TOPEX/POSEIDON have been a boon for El Niņo researchers, who have been able to track three El Niņo events since the satellite's launch in August 1992.
"The recent data are showing us that a large warm water mass with high sea-surface elevations, about six inches (15 centimeters) above normal, is occupying the entire tropical Pacific Ocean east of the international date line. In fact, the surface area covered by the warm water mass is about one-and-a- half times the size of the continental United States," Fu said. "We watched this warm water mass travel eastward from the western Pacific along the equator earlier this spring. Right now, sea- surface height off the South American coast is 10 inches (25 centimeters) higher than normal, which is comparable with the conditions during the so-called 'El Niņo of the century' in 1982-83."
In addition, recent atmospheric water vapor data collected from NASA's Upper Atmosphere Research Satellite (UARS) show tell- tale signs of an El Niņo condition in the tropical Pacific Ocean.
"The Microwave Limb Sounder experiment on UARS is detecting an unusually large build-up of water vapor in the atmosphere at heights of approximately eight miles (12 kilometers) over the central-eastern tropical Pacific. Not since the last strong El Niņo winter of 1991-92 have we seen such a large build- up of water vapor in this part of the atmosphere," said JPL's Dr. William Read. "Increased water vapor at these heights can be associated with more intense wintertime storm activity from the 'pineapple express,' a pattern of atmospheric motions that brings tropical moisture from Hawaii to the southwestern United States. This phenomenon is an example of how the ocean and atmosphere work together to dictate the severity of El Niņo events."
An El Niņo is thought to be triggered when steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows the large mass of warm water that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. This displaced pool of unusually warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. The change in the wind strength and direction also impacts global weather patterns.
In May, NOAA issued an advisory regarding the presence of the early indications of El Niņo conditions. Subsequent El Niņo forecast activities supported by NOAA indicate the likelihood of a moderate or strong El Niņo in late 1997. The forecast model operated at NOAA's National Centers for Environmental Prediction used data collected by the TOPEX/POSEIDON satellite.
"The added amount of oceanic warm water near the Americas, with a temperature between 70-85 degrees Fahrenheit, is about 30 times the volume of water in all the U.S. Great Lakes combined," said Dr. Victor Zlotnicki, a TOPEX/POSEIDON investigator at JPL. "The difference between the current, abnormally high amount of heat in the near-surface waters and the usual amount of heat in the same area is about 93 times the total energy from fossil fuels consumed by the United States in 1995."
On-going NOAA advisories on El Niņo conditions are available on the Internet.
The climatic event has been given the name El Niņo, a Spanish term for a "boy child," because the warm current first appeared off the coast of South America around Christmas. Past El Niņo events have often caused unusually heavy rain and flooding in California, unseasonably mild winters in the Eastern United States and severe droughts in Australia, Africa and Indonesia. Better predictions of extreme climate episodes like floods and droughts could save the United States billions of dollars in damage costs. El Niņo episodes usually occur approximately every two to seven years.
Developed by NASA and the French Centre National d'Etudes Spatiales (CNES), the TOPEX/POSEIDON satellite uses an altimeter to bounce radar signals off the ocean's surface to get precise measurements of the distance between the satellite and the sea surface. These data are combined with measurements from other instruments that pinpoint the satellite's exact location in space. Every ten days, scientists produce a complete map of global ocean topography, the barely perceptible hills and valleys found on the sea surface. With detailed knowledge of ocean topography, scientists can then calculate the speed and direction of worldwide ocean currents.
The Microwave Limb Sounder instrument was originally designed to study atmospheric ozone depletion, but scientists have devised new ways of using the data to study atmospheric water vapor. The Upper Atmosphere Research Satellite is completing its sixth year of operation after being designed for only a two-year mission, and is conducting an extended mission of longer-term global monitoring.
The Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, CA, manages the TOPEX/POSEIDON mission and the MLS instrument for NASA's Mission to Planet Earth enterprise, Washington, DC. The UARS satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
NASA's Mission to Planet Earth is a long-term science research program designed to study the Earth's land, oceans, air, ice and life as a total system.
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