Friday, December 23, 2011

1199027884.txt

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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Attachment Converted: "c:\eudora\attach\ForsterOzoneCooling.pdf"

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