Thursday, December 22, 2011


From: "Michael E. Mann" <>
To: Keith Briffa <>, Tim Osborn <>
Subject: [Fwd: Re: GKSS results]
Date: Fri, 13 Oct 2006 12:04:50 -0400
Cc: Caspar Ammann <>


I also figured this might be what you say, and I understand where you've
coming from. This represents a bit of a dillemma too, as it seems
unprofessional at best that Zorita and Von Storch have not made their
code public, when we of course have made ours public.

There are other sources where we could have gotten the GKSS data--I'm
checking w/ Caspar for confirmation. I know that the Cane group has it,
and I believe other groups have it nows too. So frankly, it is
effectively now 'public domain' whether VS and Zorita like it or not!

I propose, hoping that their is no loud objection, that we will include
a line in our response indicating that we have confirmed that we get
similar results using the GKSS Erik simulation. We'll leave it at that.
We don't need to show that result necessarily, unless the
editor/reviewers demand to see proof, and we certaintly don't have to
reveal where we got the GKSS data. As I mentioned, there are enough
groups out there that now have it, that VS and Zorita would not know the
source, and we would not reveal it.

We feel as if we cannot completely hide the fact that we have confirmed
our result w/ GKSS, hence the "compromise" suggested above. Meanwhile,
we can pursue a more thorough, official collaborative effort in the future.

Thoughts on this?



Michael E. Mann
Associate Professor
Director, Earth System Science Center (ESSC)

Department of Meteorology Phone: (814) 863-4075
503 Walker Building FAX: (814) 865-3663
The Pennsylvania State University email:
University Park, PA 16802-5013

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Date: Fri, 13 Oct 2006 16:36:51 +0100
From: Keith Briffa <>
Subject: Re: GKSS results
Cc: Tim Osborn <>
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Tim and I have discussed this round and round and our response is attached

what do you think

best wishes Keith

At 17:33 10/10/2006, you wrote:
>Dear Tim/Keith,
>I hope all is well with both of you.
>We've been doing a number of sensitivity tests w/ RegEM using both
>the CSM simulation, and now more recently the GKSS simulation data
>we got from you. There are some methodological developments we'll
>describe soon, related to what is the most reliable regularization
>method in RegEM, ridge regression and truncated total least squares.
>We are now leaning towards the latter because of potential
>non-convergence problems in some cases w/ the former. More on that soon.
>More relevant, however, are the results. As you can see from the
>attached plot, RegEM works quite well w/ GKSS, using a short
>calibration period (1900-1980, corresponding to years 900-980 in the
>attached plot) and both white and red pseudoproxy noise (we used
>rho=0.5 in the attached, but similar result for other values).
>The most interesting result is that while RegEM reconstructs the
>full NH series well throughout, in the case of the CSM simulation,
>it does modestly underestimate the warmth of the earliest centuries
>in the GKSS Erik simulation (it fits everything else, including the
>LIA cooling, very well). We feel that this is likely due to problem
>of correctly identifying the 'drift' pattern using CFR methods.
>The long and short of this is that we would like to be able to show
>this result in a (very short!) J. Climate response we need to
>finalize, to a comment on Mann et al (2005) J. Clim by Zorita and
>Von Storch. We would show you this response for comment of course,
>and would add you as co-authors. We have cleared with Andrew Weaver
>that this would be an acceptable course of action. We are hoping
>you are in agreement with this?
>please let us know ASAP, we have to finalize our response within days.
>Michael E. Mann
>Associate Professor
>Director, Earth System Science Center (ESSC)
>Department of Meteorology Phone: (814) 863-4075
>503 Walker Building FAX: (814) 865-3663
>The Pennsylvania State University email:
>University Park, PA 16802-5013

Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784

Attachment Converted: "c:\documents and settings\tim osborn\my documents\eudora\attach\letter to Mike - 131.10.06.doc"

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