El Niño's last hurrah?

Recent sea-level height data from the NASA/European Ocean Surface Topography Mission/Jason-2 oceanography satellite show that a large-scale, sustained weakening of trade winds in the western and central equatorial Pacific during late-January through February has triggered yet another strong, eastward-moving wave of warm water, known as a Kelvin wave.

Now in the central and eastern equatorial Pacific, this warm wave appears as the large area of higher-than-normal sea surface heights (warmer-than-normal sea surface temperatures) between 150 degrees west and 100 degrees west longitude. A series of similar, weaker events that began in June 2009 initially triggered and has sustained the present El Niño condition.

JPL oceanographer Bill Patzert says it's too soon to know for sure, but he would not be surprised if this latest and largest Kelvin wave is the "last hurrah" for this long-lasting El Niño.

Patzert explained, "Since June 2009, this El Niño has waxed and waned, impacting many global weather events. I,and many other scientists, expect the current El Niño to leave the stage sometime soon. What comes next is not yet clear, but a return to El Niño's dry sibling, La Niña, is certainly a possibility, though by no means a certainty. We'll be monitoring conditions closely over the coming weeks and months."

An El Niño also causes unusual changes in atmospheric circulation and convection around the globe. JPL's Microwave Limb Sounder instrument on NASA's Aura spacecraft captured a large eastward shift of deep convection from the current El Niño, indicated by large amounts of cloud ice in the upper troposphere.

For more information, visit: http://photojournal.jpl.nasa.gov/catalog/?IDNumber=pia12961