Oscillation Rules as the Pacific Cools

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

IMAGE ADVISORY: 2008-231 Dec. 9, 2008

Oscillation Rules as the Pacific Cools

PASADENA, Calif. -- The latest image of sea-surface height measurements from the
U.S./French Jason-1 oceanography satellite shows the Pacific Ocean remains locked in a
strong, cool phase of the Pacific Decadal Oscillation, a large, long-lived pattern of
climate variability in the Pacific associated with a general cooling of Pacific waters. The
image also confirms that El Niño and La Niña remain absent from the tropical Pacific.

The new image is available online at:
http://www.nasa.gov/topics/earth/features/20081209.html .

The image is based on the average of 10 days of data centered on Nov. 15, 2008,
compared to the long-term average of observations from 1993 through 2008. In the
image, places where the Pacific sea-surface height is higher (warmer) than normal are
yellow and red, and places where the sea surface is lower (cooler) than normal are blue
and purple. Green shows where conditions are near normal. Sea-surface height is an
indicator of the heat content of the upper ocean.

The Pacific Decadal Oscillation is a long-term fluctuation of the Pacific Ocean that
waxes and wanes between cool and warm phases approximately every five to 20 years. In
the present cool phase, higher-than-normal sea-surface heights caused by warm water
form a horseshoe pattern that connects the north, west and southern Pacific. This is in
contrast to a cool wedge of lower-than-normal sea-surface heights spreading from the
Americas into the eastern equatorial Pacific. During most of the 1980s and 1990s, the
Pacific was locked in the oscillation's warm phase, during which these warm and cool
regions are reversed. For an explanation of the Pacific Decadal Oscillation and its present
state, see: http://jisao.washington.edu/pdo/ and http://www.esr.org/pdo_index.html .

Sea-surface temperature satellite data from the National Oceanic and Atmospheric
Administration mirror Jason sea-surface height measurements, clearly showing a cool
Pacific Decadal Oscillation pattern, as seen at:
http://www.cdc.noaa.gov/map/images/sst/sst.anom.gif .

"This multi-year Pacific Decadal Oscillation 'cool' trend can cause La Niña-like impacts
around the Pacific basin," said Bill Patzert, an oceanographer and climatologist at
NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The present cool phase of the
Pacific Decadal Oscillation will have significant implications for shifts in marine
ecosystems, and for land temperature and rainfall patterns around the Pacific basin."

According to Nathan Mantua of the Climate Impacts Group at the University of
Washington, Seattle, whose research contributed to the early understanding of the Pacific
Decadal Oscillation, "Even with the strong La Niña event fading in the tropics last spring,
the North Pacific's sea surface temperature anomaly pattern has remained strongly
negative since last fall. This cool phase will likely persist this winter and, perhaps,
beyond. Historically, this situation has been associated with favorable ocean conditions
for the return of U.S. west coast Coho and Chinook salmon, but it translates to low odds
for abundant winter/spring precipitation in the southwest (including Southern
California)."

Jason's follow-on mission, the Ocean Surface Topography Mission/Jason-2, was
successfully launched this past June and will extend to two decades the continuous data
record of sea surface heights begun by Topex/Poseidon in 1992. The new mission has
produced excellent data, which have recently been certified for operational use. Fully
calibrated and validated data for science use will be released next spring.

JPL manages the U.S. portion of the Jason-1 mission for NASA's Science Mission
Directorate, Washington. JPL is managed for NASA by the California Institute of
Technology in Pasadena.

For more information on NASA's ocean surface topography missions, visit
http://sealevel.jpl.nasa.gov/ . To view the latest Jason-1 data, visit
http://sealevel.jpl.nasa.gov/science/jason1-quick-look/ .

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