El Niño 2014/15?

[elz]

La vedo da questo:
Climate Prediction Center - Monitoring & Data: Ocean Niño Index Changes Description


tsiersstv4_170-240E_-5-5N_nyr0.png


Nell'ultimo periodo la tendenza verso la nina/ipo- ha invertito il trend, il dato osservato è un mix di trend secolare al riscaldamento e variabilità naturale (e più variabilità tanto più è breve il periodo).

e comunque le oiv non sono idonee per i trend di lungo termine.
https://www.climate.gov/comment/1129#comment-1129

Hopefully we will have a blog post in the future on this subject, but we strongly recommend using continuous “historical reconstructions” (i.e. ERSST, HadSST) to place the current El Nino in historical context. The primary reason for this is b/c the dataset creators spend a lot of time and effort to ensuring that the different observing systems, which are changing through history, are placed on equal footing. In other words, there is effort made to make sure the SST values today are adjusted so they can be compared to SST values of the past.

OISST is only used at NCEP because it is updated on a sub-monthly basis which the historical reconstructions do not provide. We require datasets like OISST to initialize our models or provide some information on a sub-monthly basis. But OISST has data ingests that are not corrected for, which means biases change over time. For example, a satellite in 1997 is different from today’s satellite (and keep in mind there are also corrections needed to get from the top-of-the-atmosphere to the surface).