Reported March 2007

BACKGROUND: NASA satellite data indicates El Niņo has returned to the tropical Pacific Ocean, noting a general warming of ocean temperatures and a rise in sea surface heights in the central and eastern Pacific along the equator. These are indicators of a developing El Niņo. However, it is relatively weak and may not persist, since it is much less intense than the last major El Niņo episode in 1997-1998. If the ocean waters continue to warm and spread eastward, the effect will strengthen, perhaps brining much-needed rainfall to the southwestern and southeastern United States during the remainder of this winter.

ABOUT EL NIŅO: El Niņo is a cyclical warming of the ocean waters in the central and eastern tropical Pacific that generally occurs every three to seven years, usually around the holidays. It is associated with changes in air pressure and the movement of high-level winds and can affect weather worldwide. In the United States, En Niņo normally results in warmer-than-normal temperatures across the northern and western states. Wetter conditions result in the south, with dry weather across the Ohio Valley and Pacific Northwest. El Niņo typically peaks during the winter months. It alternates with La Niņa, the cooling of ocean waters in the same region of the Pacific.

IS IT RELATED TO GLOBAL WARMING? Scientists don't discount the possibility, but there is very little information available linking El Niņo to global warming. That's because little is known about the cause of El Niņo, although scientists do have a good understanding of how the effect evolves once it begins. El Niņos in different years can vary greatly in strength, indicating it is very sensitive to large-scale climate change. But we won't have a statistically significant sampling of such events for at least another 100 years.

The American Meteorological Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

William Patzert, Ph.D.
Jet Propulsion Laboratory
(818) 354-5395

American Meteorological Society
Boston, MA 02108-3693
(617) 227-2425
http://www.ametsoc.org

FACTOID...

The name El Niņo means "the little boy" or "Christ child" in Spanish, so called because it tends to arrive around Christmas. La Niņa means "the little girl." The first modern scientific description of the mechanics of El Niņo was made by Jacob Bjerknes of the University of California, Los Angeles in 1969.

ON THE WEB...

NASA Data Captures El Niņo's Return in the Pacific (Article)

Ocean Surface Topography From Space

National Weather Service Climate Prediction Service