Anthony Watts draws attention to a new Nature article (LI et al 2011) purporting to reconstruct El Nino activity.
The Supplementary Information shows a very obvious Chladni pattern, that went unnoticed by the Nature reviewers.
The eigenvector shown here is what one would expect from principal components carried out on spatially autocorrelated data on a geometric region of the shape shown (which equate to Chladni patterns.)
The weights of the first eigenvector are somewhat over-concentrated in the center and under-weighted on the periphery. A simple average is more meaningful.
Some CA readers may recall that a featured Nature article in 2009 (Steig et al) also misinterpreted Chladni patterns. See here for a discussion. Also see http://climateaudit.org/tag/chladni/ for other discussions.
We reported this in the initial submission of O’Donnell et al 2010. Eric Steig as “Reviewer A” required that we remove the observation that Steig’s supposedly “significant” eigenvectors were merely Chladni patterns – a requirement that we reluctantly acquiesced in, as neither reviewer Steig nor Journal of Climate editor Broccoli disclosed Steig’s adverse interest in the review.
(As I’ve previously observed – and my view here is not necessarily the same as Ryan’s-, I think that responding to Steig’s reviews diminished the quality of the eventual publication, with the loss of the Chladni section being an important loss.)
As “Reviewer A”, Steig argued that Chladni patterns were already well known to practitioners in the field – obviously not well enough known to avoid practitioners and reviewers from falling into the same error in two recent Nature articles.