ScienceDaily (Oct. 28, 2011) — El Niño and La Niña, the climate's two enfants terribles, arise with the onset of eastward migration of the tropical western Pacific's immense warm-water reservoir, the "warm pool." IRD researchers and their partners recently found two parameters useful for observing the way this pool moves: water salinity and colour.
http://www.sciencedaily.com/releases/2011/10/111028082117.htm