cc: "Tim Osborn" date: Thu Dec 1 10:42:18 2005 from: Keith Briffa subject: Re: ENSO and Hadcm3 to: "Rob Wilson" , "Brohan, Philip" Rob et al this looks good on the surface and would have been well worth including - IF - as you say , the Cook and the Mann reconstructions had been independent. I do not believe they are. Surely Mann included the Texas/Mexico tree-ring data (produced largely by Stahle) in predictors - perhaps in the form of major PC amplitude series ? We need to check this . I am sure these are the major contributer to Ed's reconstruction . At 14:26 30/11/2005, Rob Wilson wrote: Hi Philip, Tim and Keith, if you have a minute, any comments on my musings below would be greatly appreciated. thanks Rob ---------------------- in trying to address some of Mike Evans' comments, I am going to add an extra section to the paper - essentially comparing the reconstruction and models to ENSO. Spectral analysis (MTM) of the coral recon, and the ALL run for HADCM3 identifies significant (99%) spectral peaks at secular (>~90 yrs) scales and within the ENSO bandwidth. ECHO-G does not show any ENSO equivalent spectral peaks at this high confidence limit, although some spectral peaks are identified at the 95% level. In general the MTM spectra for the coral recon and HADCM3 ALL are surprisingly similar - see attached. However, after high pass filtering the time series with an 8 yr Gaussian filter, there is little coherence between the coral recon and HADCM3 (r = -0.03) I chose Ed's NINO3 TR based reconstruction for comparative analysis - he reconstructed Dec-Feb NINO3 SSTS back to 1408. This reconstruction is completely independent to the coral recon. I thought this better than Mann's NINO3 recon as it included some coral data. Anyway, after high pass (8 yr) filtering, over the 1870-1978, the correlation between instrumental annual tropical SSTs and Dec-Feb NINO3 SSTs = 0.76. The correlation between the coral recon and TR NINO3 recon over the same period = 0.47. Weaker, but the series are after all independent. Again, there is no coherence between HADCM3 and Ed's NINO3 recon. So - if I interpret these results correctly, HADCM3 does portray variability at the ENSO time-scale, but this variability has NOT been 'tuned' to the real world - i.e. the model all run does not correlate with reality. I am sure I am not the first to notice this - is there any relevant references? -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [1]http://www.cru.uea.ac.uk/cru/people/briffa/