From: Susan Solomon <Susan.Solomon@noaa.gov>
To: Tom Wigley <wigley@ucar.edu>, "Thomas.R.Karl" <Thomas.R.Karl@noaa.gov>
Subject: Re: Douglass et al. paper
Date: Sun, 30 Dec 2007 10:18:04 -0700
Cc: John.Lanzante@noaa.gov, carl mears <mears@remss.com>, "David C. Bader" <bader2@llnl.gov>, "'Dian J. Seidel'" <dian.seidel@noaa.gov>, "'Francis W. Zwiers'" <francis.zwiers@ec.gc.ca>, Frank Wentz <frank.wentz@remss.com>, Karl Taylor <taylor13@llnl.gov>, Leopold Haimberger <leopold.haimberger@univie.ac.at>, Melissa Free <Melissa.Free@noaa.gov>, "Michael C. MacCracken" <mmaccrac@comcast.net>, "'Philip D. Jones'" <p.jones@uea.ac.uk>, santer1@llnl.gov, Sherwood Steven <steven.sherwood@yale.edu>, Steve Klein <klein21@llnl.gov>, "Thorne, Peter" <peter.thorne@metoffice.gov.uk>, Tim Osborn <t.osborn@uea.ac.uk>, Tom Wigley <wigley@cgd.ucar.edu>, myles <m.allen1@physics.ox.ac.uk>, Bill Fulkerson <wfulk@utk.edu>

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Dear All,

Thanks very much for the helpful discussion on these issues.

I write to make a point that may not be well 
recognized regarding the character of the 
temperature trends in the lowermost 
stratosphere/upper troposphere.  I have already 
discussed this with Ben but want to share with 
others since I believe it is relevant to this 
controversy at least at some altitudes.   The 
question I want to raise is not related to the 
very important dialogue on how to handle the 
errors and the statistics, but rather how to 
think about the models.

The attached paper by Forster et al. appeared 
recently in GRL.   It taught me something I 
didn't realize, namely that ozone losses and 
accompanying temperature trends at higher 
altitudes can strongly affect lower altitudes, 
through the influence of downwelling longwave. 
There is now much evidence that ozone has 
decreased significantly in the tropics near 70 
mbar.    What we show in the attached paper by 
Forster et al is that ozone depletion near 70 
mbar affects temperatures not only at that level, 
but also down to lower altitudes.  I think this 
is bound to be important to the tropical 
temperature trends at least in the 100-50 mbar 
height range, possibly lower down as well, 
depending upon the degree to which there is a 
'substratosphere' that is more radiatively 
influenced than the rest of the troposphere. 
Whether it can have an influence as low as 200 
mbar - I don't know.    But note that having an 
influence could mean reducing the warming there, 
not necessarily flipping it over to a net 
cooling.    This 'long-distance' physics, whereby 
ozone depletion and associated cooling up high 
can affect the thermal structure lower down, is 
not a point I had understood despite many years 
of studying the problem so I thought it 
worthwhile to point it out to you here.  It has 
often been said (I probably said it myself five 
years ago) that ozone losses and associated 
cooling can't happen or aren't important in this 
region - but that is wrong.

Further, the fundamental point made in the paper 
of Thompson and Solomon a few years back remains 
worth noting, and is, I believe, now resolved in 
the more recent Forster et al paper:   that the 
broad structure of the temperature trends, with 
quite large cooing in the lowermost stratosphere 
in the tropics, comparable to that seen at higher 
latitudes, is a feature NOT explained by e.g. CO2 
cooling, but now can be explained by the observed 
ozone losses.   Exactly how big the tropical 
cooling is, and exactly how low down it goes, 
remains open to quantitative question and 
improvement of radiosonde datasets.  But I 
believe the fundamental point we made in 2005 
remains true:  the temperature trends in the 
lower stratosphere in the tropics are, even with 
corrections, quite comparable to that seen at 
other latitudes.     We can now say it is surely 
linked to the now-well-observed trends in ozone 
there.     The new paper further shows that you 
don't have to have ozone trends at 100 mbar to 
have a cooling there, due to down-welling 
longwave, possibly lower down still.      Whether 
enhanced upwelling is a factor is a central 
question.

No global general circulation model can possibly 
be expected to simulate this correctly unless it 
has interactive ozone, or prescribes an observed 
tropical ozone trend.   The AR4 models did not 
include this, and any 'discrepancies' are not 
relevant at all to the issue of the fidelity of 
those models for global warming.    So in closing 
let me just say that just how low down this 
effect goes needs more study, but that it does 
happen and is relevant to the key problem of 
tropical temperature trends is one that I hope 
this email has clarified.

Happy new year,
Susan


At 6:13 PM -0700 12/29/07, Tom Wigley wrote:
>Tom,
>
>Yes -- I had this in an earlier version, but I did not want to
>overwhelm people with the myriad errors in the D et al. paper.
>
>I liked the attached item -- also in an earlier version.
>
>Tom.
>
>+++++++++++++
>
>Thomas.R.Karl wrote:
>
>>Tom,
>>
>>This is a very nice set of slides clearly 
>>showing the problem with the Douglass et al 
>>paper.  One other aspect of this issue that 
>>John L has mentioned and we discussed when we 
>>were doing SAP 1.1 relates to difference 
>>series.  I am not sure whether Ben was 
>>calculating the significance of the difference 
>>series between sets of observations and model 
>>simulations (annually).  This would help offset 
>>the effects of El-Nino and Volcanoes on the 
>>trends.
>>
>>Tom K.
>>
>>Tom Wigley said the following on 12/29/2007 1:05 PM:
>>
>>>Dear all,
>>>
>>>I was recently at a meeting in Rome where Fred Singer was a participant.
>>>He was not on the speaker list, but, in 
>>>advance of the meeting, I had thought
>>>he might raise the issue of the Douglass et 
>>>al. paper. I therefore prepared the
>>>attached power point -- modified slightly since returning from Rome. As it
>>>happened, Singer did not raise the Douglass et al. issue, so I did not use
>>>the ppt. Still, it may be useful for members 
>>>of this group so I am sending it
>>>to you all.
>>>
>>>Please keep this in confidence. I do not want 
>>>it to get back to Singer or any
>>>of the Douglass et al. co-authors -- at least 
>>>not at this stage while Ben is still
>>>working on a paper to rebut the Douglass et al. claims.
>>>
>>>On slide 6 I have attributed the die tossing 
>>>argument to Carl Mears -- but, in
>>>looking back at my emails I can't find the 
>>>original. If I've got this attribution
>>>wrong, please let me know.
>>>
>>>Other comments are welcome. Mike MacCracken and Ben helped in putting
>>>this together -- thanks to both.
>>>
>>>Tom.
>>>
>>>++++++++++++++++++++++++++++++++++++++++
>>
>>
>>--
>>
>>*Dr. Thomas R. Karl, L.H.D.*
>>
>>*/Director/*//
>>
>>NOAA's National Climatic Data Center
>>
>>Veach-Baley Federal Building
>>
>>151 Patton Avenue
>>
>>Asheville, NC 28801-5001
>>
>>Tel:  (828) 271-4476
>>
>>Fax:  (828) 271-4246
>>
>>Thomas.R.Karl@noaa.gov <mailto:Thomas.R.Karl@noaa.gov>
>>
>
>
>
>Attachment converted: Junior:Comment on Douglass.ppt (SLD3/«IC») (0022CEF5)

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