Het KNMI heeft inderdaad dat standpunt. Nu ben ik natuurlijk geen professional, maar als ik de literatuur lees, ligt het wel wat genuanceerder.
http://www.columbia.edu/~lmp/paps/butler+polvani+deser-ERL-2014.pdf
Eerder wees ik al op het verschil tussen Central Based en East based El Nino en de effecten op het NH.
Abstract
The El Ni˜no–Southern Oscillation (ENSO) is a major driver of Northern Hemisphere wintertime
variability and, generally, the key ingredient used in seasonal forecasts of wintertime surface
climate. Modeling studies have recently suggested that ENSO teleconnections might involve both
a tropospheric pathway and a stratospheric one. Here, using reanalysis data, we carefully
distinguish between the two. We first note that the temperature and circulation anomalies
associated with the tropospheric pathway are nearly equal and opposite during the warm (El
Ni˜no) and cold (La Ni˜na) phases of ENSO, whereas those associated with the stratospheric
pathway are of the same sign, irrespective of the ENSO phase. We then exploit this fact to isolate
the two pathways. Our decomposition reveals that ENSOs climate impacts over North America
are largely associated with the tropospheric pathway,
whereas ENSOs climate impacts over the
North Atlantic and Eurasia are greatly affected by the stratospheric pathway. The stratospheric
pathway, which we here define on the basis of the occurrence of one or more sudden stratospheric
warmings in a given winter, and whose signature projects very strongly on the North Atlantic
Oscillation, is found to be present 60% of the time during ENSO winters (of either phase
): it
therefore likely plays an important role in improving seasonal forecasts, notably over the North Atlantic and the Eurasian continent.
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