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Publications, presentations and other activities
Claim of solar influence is on thin ice: are solar minima associated with severe winters in Europe?
2013
by G.J. van Oldenborgh (KNMI), A.T.J. de Laat (KNMI), J. Luterbacher (Justus Liebig University Giessen), W.J. Ingram (Met Office Hadley Centre and University of Oxford), T.J. Osborn (Climatic Research Unit, University of East Anglia)
Abstract
<p>A recent paper in Geophysical Research Letters, "Solar influence on winter severity in central Europe" by Sirocko et al. claims that `weak solar activity is empirically related to extremely cold winter conditions in Europe' based on analyses of documentary evidence of freezing of the river Rhine in Germany and of the Reanalysis of the Twentieth Century (20C). Our attempt to reproduce these findings failed on multiple grounds. The documentary data appear to be selected subjectively and agree neither with instrumental observations nor with other documentary data, neither of which show a significant connection between solar activity and winter severity in Europe. The analysis of the 20C circulation and temperature is inconsistent with the time series analysis. A physically-motivated consistent methodology again fails to support the reported conclusions. We conclude that the findings of Sirocko et al. cannot be trusted.</p>
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Correlation of (a) December-February average NAO index [Jones et al., 1997] and (b) temperature in Frankfurt [Klein Tank et al., 2002] with sunspot number. (c,d) lag correlation corresponding to (a,b) up to ten years with 95% confidence intervals (estimated with a non-parametric bootstrap method [Efron and Tibshirani, 1998]). All series have been detrended. Both correlations show no significance at lag zero even at p < 0.2, and would explain less than 1% of the variance. There are correlations significant at p < 0.05 at a few lags, which is to be expected due to chance fluctuations.
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Biblographic data
| Oldenborgh, G.J. van, A.T.J. de Laat, J. Luterbacher, W.J. Ingram and T.J. Osborn, Claim of solar influence is on thin ice: are solar minima associated with severe winters in Europe? accepted, Environmental Research Letters, 2013. Abstract (html) Complete text (pdf: 2 MB) |  |
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