Saturday, December 20, 2014

The Shy Pacific

James Acker, a friend from USENET days writes from the Goddard Earth Science Data and Information Services Center about some recent results

The Pacific Ocean has been remarkably shy about its intentions this year, as many of the watched indicators have for months hovered close to (but not over) the edge of definitive El Niño conditions. Despite this uncertainty, the generally warmer-than-average waters of the Pacific have contributed to record high global surface temperatures in several recent months.  These warm waters are a significant factor if 2014 ultimately becomes the warmest calendar year ever recorded (instrumentally).
While, for the most part,  El Niño or not El Niño conditions are monitored by following physical conditions, such as sea surface temperature and height differences between the western (near Asia) and eastern Pacific (near South America).  In general sea surface temperature will rise in the central and eastern Pacific during an El Niño.

There is also an noticeable biological change associated with El Nino, a change in the color of the surface due to decreased biological activity as upwelling is limited, and fewer nutrients are found at the surface.  This reduces the amount of chlorophyll.  The associated color change can be observed from space and tells a strange tale.  There has definitely been strong surface warming extending from the western to central (Niño 4) Pacific and from there to the eastern Pacific (Niño 3 and 3,4) but the region closest to the South American coast near Peru and Ecuador has not warmed at all (Nino 1,2) which is fine for those who fish in those waters and depend on the upwelling nutrients to feed the fish they seek to catch.

Niño 3

Nino 1,2

This looks much more like what has come to be called a warm pool, central Pacific or Modoki El Niño, perhaps extending a bit more towards South America than usual (or a bit less as compared to the El Niño that your grandmother knew).  In an El Niño Modoki, the west coast of the US is hotter and drier than normal, exactly the opposite from the traditional El Niño.


Russell Seitz said...

" In an El Niño Modoki, the west coast of the US is hotter and drier than normal, "

This is consistent with Watt's observations at the AGU meeting

Mitch said...

I like all the fuss made up about 2014 being the warmest--next year likely warmer, to be exceeded again in 2-7 years with the next ENSO.

Incidentally, there is a lot of variation from ENSO to ENSO about water. The best predictor of the next few months is usually the trend.