From: Tim Osborn <t.osborn@uea.ac.uk>
To: haozx@igsnrr.ac.cn
Subject: Re: =?gb2312?B?Rnc6IFRpbXMgQW5zd2Vy?=
Date: Wed Jul  1 16:19:39 2009
Cc: Luterbacher Jürg <juerg.luterbacher@giub.unibe.ch>

   Dear Zhixin (cc Juerg),
   At 15:14 01/07/2009, you wrote:

     Do you mean Se should be the standard error from the invidual reconstruction series

   yes, that's what I mean.

      (before I got your answer, I calculated the standard error for the 5 reconstruction
     data at one time point, e.g. 1470s, it is not from the original papers given by the
     authors)?

   Ah.  I understand what you've done now.

     But my question is if the author did not publish the uncertainty, how can I deal with
     the value of Se?

   Well, the original purpose of constructing IPCC Fig. 6.10c was to display the published
   uncertainty estimates of each study.  If no uncertainties had been estimated by the
   original authors then we wouldn't have produced the figure in the first place!
   So, do you really want to produce such a figure to show the uncertainty ranges when the
   uncertainty ranges haven't been calculated before?
   If you do, then you'd need to somehow estimate the uncertainty.  You could do this
   yourself, perhaps, e.g. from the differences between each reconstruction and the
   instrumental temperatures during some overlap (calibration, or independent verification)
   period?  But this wouldn't measure any increase in uncertainty during periods when each
   reconstruction is perhaps based on less input proxy data.
   Estimating the uncertainty from the spread of individual reconstruction values in a
   particular year, like you've done, is open to criticism.  Do you really think that in a
   particular year when the three recons have very similar values that the uncertainty is much
   less than other nearby years?  If you had a high number of independent reconstructions then
   this might be ok, but with only 3 series before 1350 it is too susceptible to random
   sampling variability.

     And now I understood the meaning of 5%-95% range, I will follow this, and replot my
     figures with +-1.645SE for the half scores.
     Thank you very much again, hopefully I can give the uncertainty of reconstruction
     results over China region soon. After finished, may I send the manuscript to you and
     give us comments and suggestions?

   Yes, that would be fine.
   Tim

