Tuesday, March 27, 2012

2877.txt

cc: carl mears <mearsatXYZxyzss.com>, Phil Jones <p.jonesatXYZxyz.ac.uk>, santer1@llnl.gov, Tom Wigley <wigleyatXYZxyz.ucar.edu>, "Thorne, Peter" <peter.thorneatXYZxyzoffice.gov.uk>, Steven Sherwood <Steven.SherwoodatXYZxyze.edu>, John Lanzante <John.LanzanteatXYZxyza.gov>, "'Dian J. Seidel'" <dian.seidelatXYZxyza.gov>, Melissa Free <Melissa.FreeatXYZxyza.gov>, Frank Wentz <frank.wentzatXYZxyzss.com>
date: Tue, 04 Dec 2007 15:59:43 -0700
from: Tom Wigley <wigleyatXYZxyzr.edu>
subject: Re: [Fwd: sorry to take your time up, but really do need a scrub
to: Karl Taylor <taylor13atXYZxyzl.gov>

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Good points, Karl.

(Boy -- lucky our K/Carls have different spellings.)

We can talk about this when I'm at PCMDI on Thursday.

Tom.

===================

Karl Taylor wrote:

> Dear all,
>
> To expand on what Carl and Tom have said, what Douglass et al. show, I
> think, is that the *mean* of model results is inconsistent with
> observations above the surface, under the assumptions that
>
> 1) the individual models are taken as independent, and
> 2) unforced variability hasn't dominated the observations.
>
> Note that in the models, unforced variability is not as much of an
> issue because Douglass et al. have considered the ensemble mean when
> more than 1 realization was available from a model and across models
> the unforced variability will tend cancel out. One could look at the
> inter-ensemble variations from individual models to get an idea on the
> likely magnitude of unforced variability.
>
> Douglass et al. have *not* shown that every individual model is in
> fact inconsistent with the observations. If the spread of individual
> model results is large enough and at least 1 model overlaps the
> observations, then one cannot claim that all models are wrong, just
> that the mean is biased.
>
> My own gut feeling is that models as a group probably do indeed have a
> significant bias in simulating upper air temperature trends (but I
> don't know if that has influenced the climate sensitivity in a
> systematic way). As I recall, however, some individual models appear
> to be reasonably consistent with observations (within likely
> observational errors and variability). It remains an interesting
> problem then to track down why there is a mean bias and check whether
> that bias has any important implications.
>
> A response to Douglass et al. should certainly point out the reason
> why it is appropriate to look at the range of model results for
> purposes of determining whether individual models are consistent with
> observations.
>
> cheers,
> Karl
>
>
> The observations, if
>
> Tom Wigley wrote:
>
>> All,
>>
>> Depends on whether the runs are independent. Are models independent?
>>
>> A billion runs would indeed reduce the statistical uncertainty to near
>> zero. What is left (if one compared with absolutely correct observed
>> data)
>> is the mean model bias.
>>
>> Tom.
>>
>> ++++++++++++++++++
>>
>> carl mears wrote:
>>
>>> Hi Ben, Phil and others
>>>
>>> To me, the fundamental error is 2.3.1. Expecting the observed
>>> values to lie within
>>> +/- 2*sigma(SE) (i.e. sigma/(sqrt(N-1)) of the distribution of N
>>> model trends) is just
>>> wrong.
>>> If this were correct, we could just run the models a lot of times,
>>> say a billion or so, and have a
>>> very, very, very small sigma(SE) (assuming the sigma didn't grow
>>> much) and we'd never
>>> have "agreement" with anything. Absurd.
>>>
>>> Does IJC publish comments?
>>>
>>> -Carl
>>>
>>> At 02:09 AM 12/4/2007, Phil Jones wrote:
>>>
>>>> Ben,
>>>> It sure does! Have read briefly - the surface arguments are wrong.
>>>> I know editors have difficulty finding reviewers, but letting this
>>>> one
>>>> pass is awful - and IJC was improving.
>>>>
>>>> Cheers
>>>> Phil
>>>>
>>>>
>>>> At 17:53 30/11/2007, Ben Santer wrote:
>>>>
>>>>> Dear folks,
>>>>>
>>>>> I'm forwarding this to you in confidence. We all knew that some
>>>>> journal, somewhere, would eventually publish this stuff. Turns out
>>>>> that it was the International Journal of Climatology. Strengthens
>>>>> the need for some form of update of the Santer et al. (2005)
>>>>> Science paper.
>>>>>
>>>>> With best regards,
>>>>>
>>>>> Ben
>>>>> ----------------------------------------------------------------------------
>>>>>
>>>>> Benjamin D. Santer
>>>>> Program for Climate Model Diagnosis and Intercomparison
>>>>> Lawrence Livermore National Laboratory
>>>>> P.O. Box 808, Mail Stop L-103
>>>>> Livermore, CA 94550, U.S.A.
>>>>> Tel: (925) 422-2486
>>>>> FAX: (925) 422-7675
>>>>> email: santer1atXYZxyzl.gov
>>>>> ----------------------------------------------------------------------------
>>>>>
>>>>>
>>>>>
>>>>> X-Account-Key: account1
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>>>>> X-Mailer: QUALCOMM Windows Eudora Version 6.2.5.6
>>>>> Date: Fri, 30 Nov 2007 11:38:52 -0500
>>>>> To: santer1@llnl.gov, broccoli@envsci.rutgers.edu, mearsatXYZxyzss.com
>>>>> From: Andrew Revkin <anrevkatXYZxyzimes.com>
>>>>> Subject: sorry to take your time up, but really do need a scrub of
>>>>> this
>>>>> singer/christy/etc effort
>>>>> Mime-Version: 1.0
>>>>> Content-Type: multipart/mixed;
>>>>> boundary="=====================_67524015==_"
>>>>> X-NYTOriginatingHost: [10.149.144.50]
>>>>>
>>>>> hi,
>>>>> for moment please do not distribute or discuss.
>>>>> trying to get a sense of whether singer / christy can get any
>>>>> traction with this at all.
>>>>>
>>>>>
>>>>>
>>>>> *_ ANDREW C. REVKIN
>>>>> <http://www.nytimes.com/revkin>_*The New York Times / Environment
>>>>> / Dot Earth <http://dotearth.blogs.nytimes.com/>Blog
>>>>> <http://dotearth.blogs.nytimes.com/>620 Eighth Ave., NY, NY
>>>>> 10018-1405
>>>>> phone: 212-556-7326 fax: 509/ /-357-0965 mobile: 914-441-5556
>>>>
>>>>
>>>>
>>>> Prof. Phil Jones
>>>> Climatic Research Unit Telephone +44 (0) 1603 592090
>>>> School of Environmental Sciences Fax +44 (0) 1603 507784
>>>> University of East Anglia
>>>> Norwich Email p.jonesatXYZxyz.ac.uk
>>>> NR4 7TJ
>>>> UK
>>>> ----------------------------------------------------------------------------
>>>
>>>
>>>
>>>
>>>
>>>
>>> Dr. Carl Mears
>>> Remote Sensing Systems
>>> 438 First Street, Suite 200, Santa Rosa, CA 95401
>>> mearsatXYZxyzss.com
>>> 707-545-2904 x21
>>> 707-545-2906 (fax))
>>>
>>
>
>
>


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