The tropical Pacific Ocean is beginning to exhibit the characteristics of
a developing La Niña condition. This image shows that the gradual cooling
of the central equatorial Pacific over the past few months is continuing
and the area of low sea level (shown in blue) has decreased (cooled)
slightly over last few months. It is still uncertain, scientists say,
that this cold pool will evolve into a long-lasting, strong La Niña
situation. For a complete discussion of this evolving situation and
potential implications see: http://www.noaanews.noaa.gov/stories2006/s2559.htm.
This image of the Pacific Ocean was produced using sea-surface height
measurements taken by the U.S.-French Jason satellite. The image shows
sea surface height relative to normal ocean conditions on December 31,
2005; these sea surface heights are an indicator of the changing amount
of heat stored in the ocean.
The purple areas in this image are about 18 centimeters (7 inches) below
normal, creating a deficit in the heat supply to the surface waters. The
white areas show the sea surface is between 14 and 32 centimeters (6
to 13 inches) above normal; in the red areas, it's about 10 centimeters
(4 inches) above normal. The green areas indicate normal conditions.
A La Niña situation is essentially the opposite of an El Niño condition.
During La Niña, 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 Niña reappears every three to five
years and, if the present event strengthens, it will certainly reorganize
global weather patterns.
The U.S. portion of the Jason mission is managed by JPL for NASA's Science
Mission Directorate, Washington, D.C. Research on Earth's oceans using
Jason and other space-based capabilities is conducted by NASA's Science
Mission Directorate to better understand and protect our home planet.