The El Niño phenomenon is a devilishly irregular,
anomalous, Christmas time warming of the coastal waters
off Peru and Ecuador about every 3–6 years that has an
enormous impact on global climate. Our general reference
is the monograph of Sarachik and Cane [14], with a particular
emphasis on the ‘‘Noise or chaos? Stable or unstable?
Linear or nonlinear? Does it matter and can we tell?’’ discussion
on pages 280–283