NOAA'S ROLE IN EL NIÑO RESEARCH, MONITORING AND PREDICTION

November 16, 2006 — The NOAA Climate Prediction Center declares the onset of an El Niño episode (also known as an El Niño-Southern Oscillation or ENSO) when the three-month average sea-surface temperature departure exceeds 0.5 degree Celsius (0.9 degree Fahrenheit) in the East-Central equatorial Pacific. El Niño episodes occur about every four-to-five years and can last up to 12-to-18 months. They typically develop from March to June, reach peak intensity during December to April, and then weaken during May to July. (Click NOAA image above left for a larger view of NOAA's Sea Surface Temperature Anomalies on October 28, 2006. Please credit “NOAA.”)

What is ENSO?
The broad expanse of the tropical Pacific Ocean is home to one of the most captivating large-scale ocean-atmosphere climate patterns in the world, ENSO. Strong coupling between ocean surface temperatures and the atmosphere gives rise to a cycle that oscillates between El Niño (warm) and La Niña (cold) episodes/cycles.

In general, weather patterns typically found in the western Pacific shift to the eastern Pacific during El Niño years. During El Niño events, the easterly trade winds (winds along the equator that blow from east to west) weaken allowing warm water in the western Pacific to migrate eastward across the central and east-central equatorial Pacific. The Southern Oscillation ("SO" in ENSO) represents the atmospheric component of the cycle in which lower than normal sea-level pressure and increased precipitation occurs near the eastern equatorial Pacific and higher sea-level pressure and decreased precipitation occurs in the western equatorial Pacific (Indonesia and northern Australia) during El Niño conditions (the opposite pattern is observed during La Niña conditions). This in turn has a ripple effect on climatic conditions in far flung regions of the globe. For example, shifts in tropical Pacific sea surface temperature and precipitation affect wind patterns over much of the globe. These global wind patterns, in turn, affect the behavior of monsoons, hurricanes, winter storm and belts of strong winds aloft (i.e., jet streams). This may help explain recent shifts in the pattern of tropical precipitation and why the Atlantic hurricane season has been less active than previously expected. ENSO can have both positive and negative impacts in different parts of the world —often resulting in worldwide socioeconomic consequences (ranging from an increased flood risk in some regions of the United States to warm, dry conditions in others). (Click NOAA image to the left for a larger view of NOAA's image showing typical global El Niño impacts. Please credit “NOAA.”)

Over the past few decades, NOAA’s leadership in detecting, predicting and understanding the impacts of ENSO has enhanced seasonal climate outlooks, and resulted in more timely assessments which can be used by various user communities (water, energy and transportation managers, farmers, etc.) and the general public to prepare for and mitigate ENSO impacts. Using improved models and data from a network of buoys and satellites, NOAA predicted the effects of the 1997-1998 El Niño six-months in advance.

NOAA’s ENSO Activities
NOAA uses a variety of tools and techniques to conduct research and monitor/forecast ENSO-related changes in the tropical Pacific Ocean and the impact of those changes on global weather patterns. NOAA’s ENSO activities are an excellent example of an integrated “One NOAA” approach to agency operations in that all NOAA line offices make contributions to ENSO efforts. The many parts of NOAA involved in these efforts play an essential role in meeting NOAA's mission goal to understand climate variability and change to enhance society's ability to plan and respond. (Click NOAA image to the right for a larger view of figure showing normal vs. El Niño conditions. Please credit “NOAA.”)

ENSO Research
The NOAA Office of Oceanic and Atmospheric Research conducts ENSO research and several of the ENSO data collection and modeling systems it developed are now being used in routine NOAA operations.

• NOAA Climate Program Office: The NOAA Climate Program Office coordinates climate activities across all of NOAA. It focuses on developing broader user groups for climate products and services, leads NOAA climate education and outreach activities and coordinates international climate activities. CPO provides decision makers and the general public with a better understanding of the global climate system and useful information upon which to base decisions. These outcomes are achieved through implementation of a global observing system, focused research on understanding key climate processes, improved modeling capabilities and the development and delivery of climate information services, including those related to ENSO. Contact: Jana Goldman at (301) 713-2483.
• NOAA Earth System Research Laboratory: Physical Sciences Division: Numerous research initiatives help improve future predictions of climate events. The NOAA Earth System Research Laboratory’s Physical Sciences Division in Boulder, Colo., studies the nature and causes of climate variations on time scales ranging from months to centuries, including those associated with ENSO. ESRL/PSD strives to advance the understanding and prediction of ENSO, improve monitoring and descriptions of climate variability, identify major patterns of climate variability on time scales a decade and beyond and investigate the air-sea interaction, which causes much of the climate's variability. The current El Niño event provides ESRL/PSD with an opportunity for additional research to improve future climate forecasts and applications. Contact: Anatta at (303) 497-6288.
• NOAA Pacific Marine Environmental Laboratory: The NOAA Pacific Marine Environmental Laboratory in Seattle, Wash., and Newport, Ore., is a leader in developing ocean observational systems to address NOAA's mission. PMEL's Tropical Atmosphere Ocean moored buoy array monitors ENSO events and was implemented through a multi-national effort led by PMEL. PMEL and its partners developed, installed and now maintain a network of approximately 70 moored buoys in the equatorial Pacific that provide important data about low-level atmospheric and sea surface conditions (including wind direction and speed, air temperature , humidity and temperature of the ocean at the sea surface and at various depths to 500 meters (1,640 feet). A few buoys also measure currents, rainfall and solar radiation), which is transmitted to shore in near real-time via satellite. An additional 15 moored buoys in the western Pacific are maintained by the Japan Marine Science and Technology Center. Together U.S. and Japanese moored buoys form the TAO/TRITON array. It was fully in place to capture the El Niño of 1997-98 (the largest of the 20th century) and 2002-03, providing more than six months advance warning of the impending global impacts of this climate phenomena. Therefore, the TAO array serves NOAA’s operational need by supporting ENSO forecasts (by CPC), while simultaneously providing research-quality data sets to the scientific community. (Click NOAA image above right for a larger view of a TAO buoy. Please credit “NOAA.”)
  
  Although the TAO/TRITON array broke new ground in the understanding and prediction of climate variability on seasonal and inter-annual time scales, these moored arrays cannot take sub-surface ocean measurements and have limited geographical extent. Fortunately, Argo floats do not have these limitations.
  
  Argo floats can be considered the oceanic equivalent of atmospheric weather balloons in that they travel throughout the ocean gathering and transmitting data. These highly dynamic floats can sink to a depth of about 2,000 meters (6,561 feet), travel for about 10 days following the ocean currents, and then rise to the surface to transmit information via satellite. They can provide 100,000 temperature/salinity profiles and reference velocity (i.e., current speed/direction) measurements per year. After transmitting that data they sink below the waves and repeat the process. Argo data are available from the Global Data Assembly Centers and the International Argo Project Homepage within hours after collection.
  
  Argo is an international program that calls for the deployment of 3,000 Argo floats, distributed over the global oceans at an average 3-degree spacing. The full Argo array of 3,000 floats is expected to be deployed by the end of 2006. Twenty-two countries contribute floats to the array and many others provide assistance with float deployment and access to their nation's waters. Contact: Jana Goldman at (301) 713-2483. (Click NOAA image to the right for a larger view of Curran Fey of the TAO project and Shawn Gendron of the NOAA Ship Ka'imimoana preparing to deploy a PMEL Argo float in the Tropical Pacific. Please credit “NOAA.”)
• NOAA Atlantic Oceanographic and Meteorological Laboratory: While PMEL is one of several United States float operating partners in the Argo Program, AOML handles U.S. Argo float data. In cooperation with national and international steering committees, AOML houses the NOAA Global Ocean Observing System Center, which provides an administrative umbrella that coordinates several operational oceanographic data collection to provide accurate meteorological and oceanographic data in real time from ships at sea and U.S. participation in the global ARGO program. AOML scientists manage every aspect of these programs from instrument deployment to data analysis, ensuring data quality, archiving and dissemination. Jana Goldman at (301) 713-2483
• NOAA Geophysical Fluid Dynamics Laboratory: The NOAA Geophysical Fluid Dynamics Laboratory develops high resolution global coupled (ocean and atmospheric) models for El Niño/climate change simulations. Using models developed at GFDL (and other research centers), scientists are now able to predict El Niño conditions, sometimes with lead times of a year or more. These models also have the potential to predict El Niño's effects on weather patterns over North America and other regions far from the tropical Pacific. Contact: Jana Goldman at (301) 713-2483. (Click NOAA image above right for a larger view of GFDL's El Niño/climate change simulation. Please credit “NOAA.”)

NOAA Office of Marine and Aviation Operations
The NOAA ship Ka'imimoana, home ported in Honolulu, Hawaii, supports oceanographic and climate research in the equatorial Pacific Ocean. The ship's primary mission is to deploy and service deep sea moorings that measure ocean currents, ocean temperatures and atmospheric conditions in this region. Specifically, Ka'imimoana supports a series of approximately 70 buoys known as the TAO array, which were first deployed as part of an international research program to learn how to predict the ENSO phenomenon.

As part of the NOAA research fleet, Ka'imimoana is operated, managed and maintained by civilians and officers of the NOAA Commissioned Officer Corps, one of the seven uniformed services of the United States. Contact: Jeanne Kouhestani at (301) 713-7693.

EL NIÑO MONITORING
To detect/monitor the formation, duration and strength of ENSO, NOAA set up the ENSO Observing System in 1994. Today, NOAA’s ENSO Observing System includes the TAO/TRITON moored and the Argo drift buoys — both described earlier — as well as NOAA’s polar orbiting satellites. Other components of the ENSO Observing System include the NOAA National Weather Service’s Voluntary Observing Ship program and a NOAA tide gage network to monitor sea level changes. Note that sea level observations are used in El Niño monitoring because the warming in the eastern tropical Pacific causes the water to expand, subsequently increasing sea levels anywhere from inches to as much as a foot. El Niño induced decreases in atmospheric pressures in the eastern tropical Pacific may also contribute to rising sea levels in this region. Sea level data are available on-line from the NOS/Oceanographic and Services Division and the NOAA-funded University of Hawaii Sea Level Center. The ENSO Observing System can carry out measurements from the ocean surface and its sub-surface layers and relays that data to forecast centers (such as the NOAA Climate Prediction Center) in the United States in near real time. It has also greatly improved data monitoring and coverage in the equatorial Pacific where regular and routine observations are essential to understanding and predicting ENSO. (Click NOAA image above right for a larger view of GFDL's El Niño/climate change simulation. Please credit “NOAA.”)

NOAA National Environmental Satellite, Data, and Information Service
NOAA uses several different types of satellite imagery to detect the presence of ENSO:

• The NOAA Satellite and Information Service operates two polar-orbiting environmental satellites (also known as POES) that obtain data used for studying and forecasting ENSO. Specifically, NESDIS has produced accurate sea surface temperatures from Advanced Very High Resolution Radiometer observations taken onboard the NOAA POES since 1982.
• NESDIS scientists also generate monthly mean rainfall charts from instruments on board the U.S. Defense Department’s Meteorological Satellite Program satellites. Measurements from the Special Sensor Microwave/Imager are particularly valuable for studying precipitation variations associated with ENSO events. ENSO greatly impacts the global distribution of precipitation, causing droughts in some regions and floods in others.
• The NOAA National Oceanographic Data Center’s Laboratory for Satellite Altimetry provides, in near-real time, sea level data from the NASA/CNES Jason-TOPEX/POSEIDON altimeter satellites. These highly accurate sea level observations are included in weekly ocean model runs, which are used by the NOAA Climate Prediction Center to update its El Niño forecasts (to be described later). Additional NOAA satellite products with relevance to ENSO are: Sea Surface Temperature (SST) Contour Charts and Sea Surface Temperature Images.
  Contact: John Leslie (301) 713-1265. (Click NOAA image above right for a larger view of the Topex/Poseidon Sea Level Deviations for July 1996, 1997 and 1998. Please credit “NOAA.”)

PREDICTING EL NIÑO
NOAA National Weather Service: Data provided by the ENSO observing system are fed into several computer models/statistical analysis at the NOAA National Centers for Environmental Prediction to predict the evolution of ENSO:

• NCEP’s Climate Forecast System is a fully coupled (ocean-atmosphere) computer model that produces monthly to seasonal climate forecasts.
• NOAA scientists also benefit from a suite of statistical methods, such as Canonical Correlation Analysis, which improves their ability to predict ENSO.
• NOAA’s Sea Surface Temperature Consolidated Forecast harnesses the skill provided by both coupled and statistical models to forecast surface temperature anomalies in the ENSO region of the central and eastern equatorial Pacific. (Click NOAA image above right for a larger view of NOAA's satellite views of El Niño. Please credit “NOAA.”)

Aided by these various predictive tools, NOAA produces several forecast discussions that incorporate the current and future status of ENSO. Specifically, the NOAA Climate Prediction Center, in Camp Springs, Md., provides climate services to users in the government, research community, private industry and the public. Currently, the CPC issues a monthly El Niño/Southern Oscillation (ENSO) Diagnostic Discussion (also printed in the Forecast Forum section of NOAA CPC’s Climate Diagnostics Bulletin) and a weekly update, the ENSO Evolution, Status and Prediction Presentation. These forecasts are available online and provide timely, accurate information on the status of ENSO.

Because ENSO is linked to numerous climate and weather impacts across the United States, NOAA has developed a suite of products that enables the user to make more timely and cost-efficient decisions when an ENSO event is predicted. To meet the needs of a diverse user community, NOAA experts produce several weekly-to-seasonal assessments and forecasts. Knowledge of ENSO (and other climate features) is applied to Seasonal Climate Outlooks (for temperature and precipitation) out to 13 months in the future. This product and the U.S. Seasonal Drought Outlook provide long-range predictive information on temperature and precipitation anomalies in the United States. Products like the U.S. Hazards Assessment provide users with decision-making information on timescales of three to 14 days. Climate Assessments are also issued for special events of interest, such as significant ENSO episodes. NOAA plays an important role by translating its understanding of ENSO into integrated products that benefit the user community. (Click NOAA image above right for a larger view of U.S. Seasonal Drought Outlook from Oct. 19, 2006 to January 2007. Please credit “NOAA.”)

Many other offices within the NOAA National Weather Service are also actively engaged in the El Niño event, providing the nation with climate and weather warnings, forecasts and information. For example, information about current flood events is available from NWS field offices and the Hydrologic Information Center. Likewise, NWS field offices and River Forecast Centers are also working with local communities regarding the possible impacts of ENSO and preparedness efforts. Contact: Carmeyia Gillis at (301) 713-8000, ext. 7163.

NOAA National Marine Fisheries Service
ENSO related warming of the central and eastern equatorial Pacific can have a significant impact on marine life. The NOAA National Marine Fisheries Service is studying the effect of El Niño and other climate events on the marine environment. (Click NOAA image to the right for a larger view of June, 1997 Sea Surface Temperature Anomaly - CoastWatch West Coast Regional Node. The image shows increased sea surface temperatures associated with the 1997 El Niño. Please credit “NOAA.”)

• NOAA Northwest Fisheries Science Center: Scientists at the NOAA NWFSC have several ongoing research projects that will contribute to the greater understanding of how El Niño events impact marine resources. For example, the NWFSC scientists at the Newport Field Station along the central Oregon coast have been investigating relationships among nutrient rich coastal upwelling (which is usually suppressed during El Niño years), ocean conditions, zooplankton production and predator and forage fish interactions on the growth and survival of juvenile salmon and steelhead as they first enter the marine environment. Although this project was not specifically designed to focus on the impacts of El Niño, the timely start of this work (particularly the oceanographic sampling) prior to the onset of the 1997 El Niño and continued monitoring during and after the event provided important information on the impacts of El Niño. Similar studies on ichthyoplankton and forage fish (sardines, anchovy, etc.) are also being conducted from Grays Harbor, Wash., to Heceta Bank, Ore. The time-series of ichthyoplankton and forage fish densities and distribution over this large coastal area will provide an important data set for prospective analyses of the impacts of El Niño. Contact: Vicky Krikelas, (206) 860-3263.
• NOAA Fisheries Service Southwest Fisheries Science Center: The NOAA Fisheries Service Southwest Fisheries Science Center in La Jolla, Calif., collaborates with Scripps Institution of Oceanography and the NOAA Office of Oceanic and Atmospheric Research to study California offshore waters in order to expand current information about the impact of El Niño on marine fisheries and the ocean environment. Contact: Jim Milbury, (562) 980-4006.
  

Relevant Web Sites
El Niño/southern Oscillation (ENSO) Diagnostic Discussion

NOAA’s El Niño Southern Oscillation

NOAA Satellite Images of Sea Surface Temperature Anomalies

What is the latest El Niño data?

NOAA ISSUES UNSCHEDULED EL NIÑO ADVISORY
El Niño Makes a Comeback

Media Contact:
Carmeyia Gillis, NOAA Climate Prediction Center, (301) 763-8000 ext. 7163 or NOAA National Weather Service Public Affairs, (301) 713-0622