cc: Henry Pollack date: Tue, 26 Jul 2005 14:27:29 -0400 (EDT) from: Jason E Smerdon subject: Re: NH Borehole Timeseries to: Tim Osborn Hi Tim, Attached are three borehole reconstruction time series for the Southern Hemisphere, Africa and Australia. I have also included a pdf file containing the plots for the three series and the corresponding SAT time series that I used to reference the boreholes. There are several things to keep in mind with regard to the SH reconstructions. The SH dataset is much smaller than the NH dataset. There are a total of 165 sites in the SH, as compared to the 695 sites in the NH. The African and Australian subsets include 92 and 57 sites, respectively. The SH hemisphere is therefore much more sparsely sampled. As such, we have only computed point averages in each of the included reconstructions and noise may be more of a factor in the SH than in the NH. Additionally, more than half of the holes in the SH were measured before 1980. While this is true of places in the NH as well, the hemisphere includes many more measurements during the 80s and 90s. Many of the measurements in the SH therefore have missed much of the extreme warming in the latter two decades of the 20th century. We have taken this into account by referencing the boreholes to shortened periods in the 20th century SAT record, i.e., we used SAT trends from 1900 (1910 in the case of Australia) to the median borehole logging dates. The fact that the boreholes have not measured the late 20th-century warming is clearly visible in each of the plots that I have included. Each of the above points necessitate cautious interpretations of the SH record. Given that the provided reconstructions have been assembled in a bit of a hurry, Henry and I hope that we will have further chances to refine the reconstructions themselves (if needed) and their subsequent interpretation. It would also be very helpful to see the ensemble comparison including all of the SH reconstructions once it is completed. In the meantime, let me know if you need anything else. I hope that all is well. Best of luck with the IPCC duties and I hope that the included reconstructions are helpful. Take Care, Jason ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ____ ____ Jason E. Smerdon, Ph.D. [ \ / ] Dept. of Geological Sciences | \/ | University of Michigan | | 1100 N. University Ave. | |\/| | Ann Arbor, MI 48109-1005 | | | | Phone: (734) 657-9747 [____] [____] Fax: (734) 763-4690 E-mail: jsmerdon@umich.edu Web: http://www-personal.umich.edu/~jsmerdon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\SH_Reconstructions.pdf" Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\African_Reconstruction.txt" Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\Australian_Reconstruction.txt" Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\SH_Reconstruction.txt"