  The main objective of this article is to establish a new mechanism of the El
Nino Southern Oscillation (ENSO), as a self-organizing and self-excitation
system, with two highly coupled processes. The first is the oscillation between
the two metastable warm (El Nino phase) and cold events (La Nina phase), and
the second is the spatiotemporal oscillation of the sea surface temperature
(SST) field. The interplay between these two processes gives rises the climate
variability associated with the ENSO, leads to both the random and
deterministic features of the ENSO, and defines a new natural feedback
mechanism, which drives the sporadic oscillation of the ENSO. The new mechanism
is rigorously derived using a dynamic transition theory developed recently by
the authors, which has also been successfully applied to a wide range of
problems in nonlinear sciences.
