(
2014-07-11)
Karnauskas, Kristopher B.; Murphy, Lisa N.
The present study is an investigation into the physical underpinnings of the phase
locking between ENSO and the annual cycle. An appreciable amount of work has been
aimed at this and similar questions, particularly observational studies resulting from the
TOGA decade. In contrast, relatively little modeling efforts have been directed at
understanding why peak conditions of most El Nino events in recent decades have
occurred in boreal winter. Current knowledge of the global effects of El Nino remains
based on observations of El Nino impacting the Earth during boreal winter. Using an
OGCM of the tropical Pacific Ocean and various in situ data, it is found that the first
order explanation of the seasonal timing of ENSO events, simply that westerly wind
bursts occur during that season, is far short of complete. Rather, the state of the ocean is
itself better situated thermodynamically to respond to the wind anomalies that are
believed to play an important role in the genesis of El Nino events.
