Can we distinguish canonical El Nino from Modoki?

Following the recent discovery of the Modoki El Nino, a proliferation of studies and debates has ensued concerning whether Modoki is dynamically distinct from Canonical El Nino, how Modoki impacts and teleconnections differ, and whether Modoki events have been increasing in frequency or amplitude. Three decades of reliable, high temporal-resolution observations of coupled ocean-atmosphere variability in the equatorial Pacific reveal a rich diversity of El Ninos. Although central and eastern Pacific sea surface temperature (SST) anomalies appear mechanistically separable in terms of local and remote forcing, their frequent overlap precludes robust classifications. All observed El Ninos appear to be a mixture of locally (central Pacific) and remotely forced (eastern Pacific) SST anomalies. Submonthly resolution appears essential for this insight and for the proper dynamical diagnosis of El Nino evolution; thus, the use of long-term monthly reconstructions for classification and trend analysis is strongly cautioned against.