Tuesday, December 20, 2011

1143819006.txt

From: Tim Osborn <t.osborn@uea.ac.uk>
To: "Brooks Hanson" <bhanson@aaas.org>
Subject: Re: data request to SCIENCE for 1120514
Date: Fri, 31 Mar 2006 10:30:06 +0100
Cc: "Jesse Smith" <hjsmith@aaas.org>,Keith Briffa <k.briffa@uea.ac.uk>

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Dear Brooks Hanson,

of the two additional questions/requests, the first one is quick to
respond to and so I can do that immediately.

In fact my previous reply answers the first question already, as does
our paper itself in a very clear way. It is something of a waste of
time, therefore, to have to write another answer, but here goes anyway...

We clearly state (in the SOM to our paper) what the data sources
were, and Esper et al. was not the source for the four series in
question. There is, therefore, no need for anyone to "surmise" that
this is the case, because we explicitly state it!

Further, we state in our paragraph (d) that we replaced Athabasca
with a new, "better-replicated series" from Luckman and
Wilson. "Better-replicated" clearly indicates that there are more
data in the new series than were available to Esper et al., as is
also clear from even a cursory read of the Luckman and Wilson
paper. So it should be obvious that you cannot expect to reproduce
the results using the fuller data set by using only the more limited
data available from Esper et al. -- otherwise what would be the point
of going out and collecting all that new data?

The other three series are covered in our paragraph (c), "The data
sets contain some non-identical tree-ring series derived from the
same sites; we have favoured series from (S3) because they are based
on a greater number of tree core measurements than the series
generated by (S1)". So we clearly did not use the Esper et al. data
(S1) and it should also be clear that the series we did use can not
be reproduced using the Esper et al. data because they are
"non-identical" and there are fewer tree cores in the Esper et al.
data. The source we gave for these three series is Briffa (2000).

We did not use tree-core measurement data in our paper, only
chronologies that had previously been assembled by others from core
measurement data. I don't have any core measurement data and
therefore have none to give out! And in my first reply I explained
why I didn't think that this was appropriate anyway, since I consider
that our obligation is limited to providing data to allow the
replication of the steps reported in our paper, none of which
involved any processing of core measurement data.

I will reply next week regarding the second question/request.

Best regards

Tim

At 20:35 30/03/2006, Brooks Hanson wrote:
> Dear Dr. Osborn:
>
>Thank you for your assistance in resolving the request for data for
>your recent paper. I have passed along the relevant information you
>have provided (I assure you not your email). In response, i've received
>two additional questions. I'm wondering if it would be possible to
>clarify these.
>
>In 4 cases, the Osborn site chronology differs from the Esper site
>chronology, although in the other cases the versions are identical. In
>some cases, the date ranges do not match. I do not believe that it is
>possible to replicate the Osborn version from the Esper measurement data
>in these 4 cases and surmise that Osborn used a different measurement
>data set. I therefore request measurement data used by Osborn for the
>following sites: Polar Urals, Tornetrrask, Taymir and Athabaska.
>
>The HadCRU2 data set contains temperature data for the gridcell 37.5N,
>117.5W commencing in 1870. However, the gridcell information provided
>by Osborn commenced only in 1888 and the differences are material to
>the final result (0.045 versus 0.18 reported). What is the reason for
>commencing this comparison in 1888 rather than the available 1870? Since
>there is a material difference in this example, could you please provide
>the gridcell temperature sets in a comparable format for the other 13
>Osborn and Briffa series
>
>I appreciate that the latter request may take some additional effort as
>you noted. I'm hopeful that this will provide a resolution to this
>matter.
>
>Sincerely,
>Brooks Hanson

Dr Timothy J Osborn
Climatic Research Unit
School of Environmental Sciences, University of East Anglia
Norwich NR4 7TJ, UK

e-mail: t.osborn@uea.ac.uk
phone: +44 1603 592089
fax: +44 1603 507784
web: http://www.cru.uea.ac.uk/~timo/
sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm

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