El Niņo and La Niņa
El Niño and La Niña are part of a climate
cycle referred to as the El Niño -Southern Oscillation (ENSO).
During El Niño, warmer
than average sea surface temperatures occur in the Equatorial
central and eastern Pacific while during La Niña, cooler than
average sea surface temperatures predominate. The Southern
Oscillation ("SO" in ENSO) represents the atmospheric component
of the cycle in which lower (higher) than normal sea-level pressure occurs
near Tahiti and (higher) lower sea-level pressure occurs in Australia
during El
Niño (La Niña) conditions.
ENSO is an important component of the climate system since the El Niño/La
Niña phases impact weather on a global scale.
The impact of ENSO sea
surface temperatures (SSTs) on the atmosphere is through
the tropical response of rain-producing convection and cloud formation, the principal agents for exchanging heat from Earth's
surface. Normally, the SST is very warm in an area that covers the equatorial
Indian and west Pacific Ocean regions. During El Niño, the eastern
and central equatorial Pacific warms causing rainfall to shift several
thousand kilometers east from the western equatorial Pacific in response
to the warming of the underlying SSTs. The opposite occurs during La
Niña, with rainfall deficits in the eastern equatorial Pacific
and wet conditions confined to the western equatorial Pacific.
Some areas experience drought during El Niño and this dryness can
contribute to large-scale burning by uncontrolled wildfires.
The strong El Niño of 1982/83 has inspired innovative climate research,
which has resulted in greater predictability of El Niño/La Niña. To serve
society's need for weather and climate information and to help plan and
respond to weather and climate impacts, NOAA's research laboratories
have taken a leadership role in furthering ENSO observations and research
to improve understanding, predictions, and impacts.
Why we study ENSO
ENSO causes widespread impacts on
a global scale such as, drought, wildfires, crop failure, starvation,
increased tropical storm/hurricane activity, damage to ecosystems, flooding,
and increased spreading of infectious diseases.
It is believed that El Niño conditions suppress
the development of tropical storms and hurricanes in the Atlantic,
and that La Niña favors hurricane formation in the Atlantic.
Understanding and predicting ENSO has resulted in more accurate climate
predictions and, therefore, a reduction of its impacts through better
planning. Decision-makers are able to more effectively manage agricultural
and water resources, fisheries, and grain and fuel reserves.
How we study ENSO
NOAA's research labs provide valuable information about ENSO to the
nation and world through observations, research, and forecasting.
Data corresponding to observed climate conditions are collected
through the use of sophisticated weather instrumentation. One project,
TOGA-TAO,
was developed in response to the need for real-time data from the tropical
Pacific. NOAA's Pacific Marine Environmental Laboratory and its partners
developed this low-cost deep ocean mooring system to measure meteorological
and oceanic conditions and transmit all the data to shore in real-time
via satellite.
Abnormal ocean currents during El Niño bring warm
waters eastward from the western Pacific and leave low tides in the
western Pacific. Both can cause the bleaching and death of
corals, damaging the balance of these ecosystems.
Many aspects of the ENSO phenomenon are studied so that
there can be a better understanding of its nature and causes. For example,
researchers analyzing climate
diagnostics focus on such topics as understanding and predicting
variations in tropical sea surface temperatures (SSTs); understanding
and predicting the global impact of ENSO including identifying the global
patterns of seasonal
weather extremes;
and the probability
of occurrence of these extremes;
Scientists also have been able show how El Niños/La Niñas
impact Atlantic basin hurricane
activity through changes in the global atmospheric circulation.
NOAA research scientists are now taking their understanding
of ENSO a step further by comparing comprehensive descriptions
of these events from the observed record with those simulated by numerical
prediction models, which are computer programs designed to represent
physical processes that occur in nature via mathematical equations.
Scientists study El Niño in the tropical
Pacific Ocean because it is the most common and powerful predictor
of seasonal climate change.
NOAA researchers continue to work with scientists from
around the world to design and build an improved global
system for (1) observing the tropical oceans, (2) predicting El Niño/La Niña and other climate phenomena,
and (3) making routine climate predictions readily available for use
in decision making and planning purposes.
Much of the research done by the NOAA research laboratories
has been transitioned into useful prediction
tools offered through NOAA's operational
forecasting branch.
NOAA Research programs that study El Niño and La Niña
NOAA Climate Program Office (CPO)
Atlantic Oceanographic and Meteorological Laboratory (AOML)
Earth System Research Laboratory (ESRL)
Geophysical Fluid Dynamics Laboratory (GFDL)
Pacific Marine Environmental Laboratory (PMEL)
Additional Related Information
