Various authors have examined the strength of the equatorial Pacific overturning known as the Walker Circulation in both climate models and observations, attributing a generalized weakening to anthropogenic global warming. Here we review the analysis in Power and Smith  using updated Southern Oscillation Index (SOI) and NINO sea surface temperature indices. We find no significant long-term changes in the indices, although the SOI appears to have recovered from an anomalously low period from 1976 to 1998. The increasing sea surface temperature in the NINO4 region is not significant, nor representative of other NINO regions. The findings of a weakening Walker circulation appear to be premature, and the corresponding climate model projections cannot be substantiated at this time. The reports of weakening of horizontal atmospheric circulation in climate models should be regarded as an inconsistency and not as an indicator of anthropogenic climate change.
Comments: 16 Pages. First published 2009/8/27 at Landshape.org (http://landshape.org/enm/files/2011/01/walkerarticle.pdf)
[v1] 2012-11-01 19:28:26
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