The k2p blog

A new article has been posted on the National Oceanic & Atmospheric Administration website and comes to the conclusion that there is an even chance that La Niña conditions could extend into 2012:

Multivariate ENSO Index (MEI) by Klaus Wolter 4th February 2011

El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales. Here we attempt to monitor ENSO by basing the Multivariate ENSO Index (MEI) on the six main observed variables over the tropical Pacific. These six variables are: sea-level pressure (P), zonal (U) and meridional (V) components of the surface wind, sea surface temperature (S), surface air temperature (A), and total cloudiness fraction of the sky (C). …… Negative values of the MEI represent the cold ENSO phase, a.k.a.La Niña, while positive MEI values represent the warm ENSO phase (El Niño)………

Discussion and comparison of recent conditions with historic La Niña events

In the context of the rapid transition of the MEI into strong La Niña conditions, this section features a comparison figure with strong La Niña events that all reached at least minus one standard deviations by June-July, and a peak of at least -1.4 sigma over the course of an event. The most recent moderate La Niña events of 1998-2001 and 2007-09 did not qualify, since they either did not reach the required peak anomaly (the first one) or became strong too late in the calendar year (both).

The updated (December-January) MEI value has strengthened slightly to -1.62 standard deviations after almost dropping below -2 standard deviations in August-September. Nevertheless, the most recent value ranks 2nd for this time of year, clearly below the 10%-tile threshold for strong La Niña MEI rankings , but slightly weaker than the value recorded in 1974. If one were to take the average of all MEI rankings since July-August (a six-month period), the strongest La Niña half-year periods of mid-55, ’73-74, and late ’75 averaged slightly stronger than the current event, for now (this is means Rank 4 for the current event, up one from last month).
Negative SST anomalies are covering much of the eastern (sub-)tropical Pacific in the latest weekly SST map. Many of these anomalies are in excess of -1C.
For an alternate interpretation of the current situation, I highly recommend reading the latest NOAA ENSO Advisory which represents the official and most recent Climate Prediction Center opinion on this subject. In its latest update (6 January 2011), La Niña conditions are expected to last “well” into the Northern Hemisphere spring of 2011. …….. While La Niña conditions are guaranteed well into 2011, it remains to be seen whether it can rally once more to cross the -2 sigma barrier, and/or whether it will indeed last into 2012, as discussed six months ago on this page. I believe the odds for a two-year event remain well above 50%, made even more likely by the continued unabated strength in various ENSO indices.

It seems self-evident ( even if not fashionable or politically correct) that the sun controls our climate and that the oceans do the sun’s bidding as they drive the atmosphere which then determines our weather.

The consequences of an extended La Niña into 2011 / 2012 could be

• another good monsoon year in India,
• a cold winter again for 2011/2012 in the Northern hemishere

Tags: El Niño-Southern Oscillation, La Nina, National Oceanic & Atmospheric Administration, Northern Hemisphere

This entry was posted on February 5, 2011 at 8:54 am and is filed under Climate, Geosciences, Weather. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.