There is an evident positive trend in the EA index computed by noaa ncep. Could it be related to climate change dynamics or is natural variability?
Added: I think the question should deserve investigation, as was viewed more than 70 times and still no-answered.
http://www.cpc.ncep.noaa.gov/data/teledoc/ea.timeseries.gif
Dear Antonio,
The problem with your question is that very a few people know about the East Atlantic pattern (EA). The Arctic oscillation (AO) index, North Atlantic Oscilation (NAO) and Northern Annular mode (NAM) have a greater popularity.
What concerns you question - the multi-decadal variability of EA simply reflects the climate variability. Note that I'm saying variability, but not irreversible climate change!
I was not talking about irreversibility, but possible relationships with climate change (anthropic driven inother words).
Thank you for you reply,
Antonio
It is a very interesting question. East Atlantic pattern spontaneously appears on GCMs, like the NAO, and other mean modes of atmospheric variability over North atlantic. The NAO showed a positive trend during the lasts decades and it was attributed to climate change because CMIP3 models projected more positive NAOs under increasing GHG emissions. However, CMIP5 models projected no changes on NAO under increasing GHGs scenarios. I think that is a very difficult task to investigate if the climate indices trends correspond to natural variability or not cause the uncertainty associated. I think this post could be interesting http://klimazwiebel.blogspot.co.uk/2012/11/now-nao.html
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