Traditional El Nio and El Ni o Modoki Revisited:Is El Nio Modoki Linearly Independent of Traditional El Nio?

The present study revisited the first two leading modes of tropical Pacific sea surface temperature anomalies (SSTA) during the period of 1979 2008.It is suggested that the so-called El Nio Modoki,which is captured by the second mode,exists objectively and exhibits obvious differences from traditional El Nio,which is captured by the first mode,in terms of its spatial characteristics.Furthermore,the authors found that El Nio Modoki is linearly independent of traditional El Nio;hence,it cannot be described as part of the traditional El Nio evolution,and vice versa.