ABSTRACT
The El Niño is defined and discussed to some extent in Quinn (1987) where it is considered to be the regional manifestation of a recurring large-scale Southern Oscillation (SO)-related ocean-atmosphere fluctuation which is primarily noted over the Indo-Pacific area. There has been some confusion in terminology as a result of using the term ENSO (El Niño/Southern Oscillation) to represent the large-scale relative. Some authors refer to this large-scale short-term climate change as an equatorial Pacific warm event (e.g., Rasmussen et al., 1983) and many others refer to the whole near-global-scale climatic change associated with these developments as El Niño. For the purposes of this chapter, it is most suitable to accept the El Niño as a regional manifestation of the parent large-scale SO-related climatic fluctuation which for the sake of simplicity we will refer to here as the ENSO. The region directly affected by the El Niño is southwestern Ecuador, northwestern Peru and their coastal waters. The following background information will provide some insight into the nature and development of this phenomenon.
