The Pacific Ocean doesn't show signs of anything that looks like the whopper El
Niño of 1997-1998, according to the latest information from the U.S.-French
ocean-observing satellite Topex/Poseidon. The data do show that the
mid-equatorial Pacific Ocean has slowly warmed by about 1 degree Celsius (1.8
degrees Fahrenheit) above normal in the past few months. However, the Pacific
continues to be dominated by the larger-than-El Niño/La Niña pattern called the
Pacific Decadal Oscillation, which may discourage El Niño development.
"Except for some recent mid-Pacific warming, June 2002 looks very much like June
2001," said oceanographer Dr. William Patzert of NASA's Jet Propulsion
Laboratory, Pasadena, Calif. "We're still in an El Niño holding pattern." (See
http://sealevel.jpl.
nasa.gov/elNiño/20010621.html for the June 2001 image.)
The ocean warming in the past month can be explained by a relaxation in the
equatorial trade winds observed by NASA's Quick Scatterometer (QuikScat)
satellite, which measures ocean wind speed and direction. These winds usually
blow from the Americas towards Asia, helping push warm water eastward. "For the
first two weeks of June, these winds were unusually weak," said Dr. Timothy Liu,
QuikScat project scientist. "But by last week, they had returned to normal. If
the weakening continued or intensified, we could have been expecting an El Niño
to develop by early fall." (See http://airsea-www.jpl.nasa.gov/ENSO.)
For the past few winters the weather- and moisture-delivering jet stream has
been steered north by the Pacific Decadal Oscillation and other planetary
patterns, resulting in a warm winter all across the United States and very dry
conditions on the East and West coasts. A large enough El Niño might provide
some relief for the drought-plagued west, southwest and southeast U.S., but it's
wishful thinking so far," Patzert added.
The Topex/Poseidon data were taken during a 10-day collection cycle ending June
14, 2002. They show that there hasn't been any fundamental change in the
ocean's large-scale patterns for the past three years. The near-equatorial ocean
has been very quiet, although sea levels and sea-surface temperatures are near
normal or slightly warmer throughout the far western and central tropical
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 warmth contrasts with the Bering Sea, Gulf of Alaska
and U.S. West Coast, where lower-than-normal sea-surface levels (blue areas) and
cool ocean temperatures continue. The blue areas are between 5 and 13
centimeters (2 and 5 inches) below normal, and the purple areas range from 14 to
18 centimeters (6 to 7 inches) below normal.
For more information, read: As Summer Starts, Next El Niño Is Slow to Grow.
Image courtesy NASA/JPL Topex and Jason Team