La Niña's in turn to wreak havoc

Image of the Month - January 2011

Sea level anomalies end of September 2010 (top) and mid-January 2011. The lower-than-normal sea surface height close to the coasts of South America are the signature of La Niña. On the opposite of the basin, high sea level anomalies can be seen close to Indonesia and the North of Australia, where heavy flooding are occuring. (see the movie for July 2010-January 2011 (mp4, 1 MB))


Sections in temperature in the Tropical Pacific for January 2010 (end of El Niño) and January 2011 (La Niña). The much warmer temperature at the East of the basin is clear on the top figure (El Niño), whereas at the bottom, one can see that the cold underlying temperature are nearly at the surface (La Niña) (Credits TAO project office/PMEL/NOAA)

La Niña is no sweeter than its brother. Last year a not-quite El Niño was playing its last tricks at about this time. This year, a La Niña is wreaking havoc on the Eastern coasts of the central Pacific, and has still some stamina to stay on till Spring. Flooding is catastrophic in the Australian state of Queensland. Mud slides in Philippines are also numerous -- and so on.

 The first "La Niña" observed by altimetry was by Geosat in 1988. Then we had to wait 1995 to see another one with  Topex/Poseidon and ERS-1. Since then (since 1992, in fact), such phenomena are closely and continuously monitored by altimetry as well as by a wealth of other techniques, including the "TAO" array that dot Tropical Pacific with moored buoys. Thanks to all those, understanding of La Niña and El Ninõ is better and better, and the warnings are also improved.

Next altimetry satellites will continue to help improve both knowledge and warning systems, so as to be able to mitigate the effects of the erratic behavior of both climatic "children".


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