Just
when it looked as if a traditional El Niño was getting its sea legs, the event
is now looking a bit less canonical. This prompted
the following analysis. This
post is jointly written by Rajan Alexander who administers the blog Rajan’s
Take: Climate Change and Rajesh
Kapadia who administers the blog, Vagaries of the Weather.
If we
take a look at last week’s US-CFS v2 forecasts for Niño regions 1+2 it could be
observed that the warmest anomalies have been centred in the eastern portion of
the ENSO monitoring area.
However, also seen in the
forecast, there is now more of a potential for the temperatures to be much
lower. One explanation is that the Niño maybe dying off!! The only other
explanation is that the heat is merely transferring westwards - a fact
validated through the latest Sea Surface Temperatures (STT) departures.
Till recently, it was thought that
the El Niño had only one mode - a periodic warming in the eastern tropical
Pacific that occurs along the coast of South America. In 2004, it was
discovered to have also a second mode that occurs around 12% of the time.
A Japanese team led by T. Yamagata
(that included a prominent Indian climatologist, Dr Venkata Ratnam) noticed the
2004 El Niño was warming more strongly in the Central Pacific region and
accordingly stumbled on the discovery of its second mode by sheer accident.
They called such an El Nino as Modokai, which is a classical Japanese word
which means “similar but different”. The phenomenon is also known
as a Pseudo or Central Pacific (CP) El Niño.
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