Friday, June 1, 2012

4753.txt

date: Thu Oct 7 10:28:36 2004
from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: Re: More vertical profile plots
to: Ben Santer <santer1atXYZxyzl.gov>

Ben,
Thanks for the plots. I gather from Karl that you'll be in Seattle and not at the HC
review.
I'll be in Seattle also and am missing the HC review, so we can catch up on things.
Last week was the first LA meeting of AR4. You have likely been contacted by
Kevin and also maybe by Brian Soden about writing something on tropopause heights.
It would perhaps be useful to send them these figures and maybe also to David Parker.
For our chapter Kevin is co-ordinating the U/A and circulation sections. I'm doing
the surface T/P and extremes and the final summary. I've been too busy to think about
anything
yet ! We have a mix of abilities in the LAs, but Brian, David P, Dave Easterling and
Albert
Klein Tank of KNMI are solid. The Iranian, Argentinian, Romanian, Kenyan don't seem up to
too much, but this is life in the IPCC - remember Ebby !
The fact that HadCRUT2v is close to PCM may be fortuitous, but good nonetheless. If
you
subsample PCM with CRU coverage, you say the PCM trend will reduce. The paper and report
with Adrian shows that if you look at the full ERA-40 surface T data, then the reverse
happens.
Not a large increase though. Most comes from the SH, so there are issues of what ERA-40
is doing over the Southern Oceans, Antarctica and Australia are key. I'll be talking about
this
work in Seattle.
I don't have any IDAG work to give you - not done a lot. Plan to look at the 1740 event
in Europe, when time permits. If you want any of my ppt for your IDAG talk, you can look
through in Seattle.
Good to catch up in a weeks time. Hope you and Nick are well. Away next week in Delhi
at a GCOS workshop.
Cheers
Phil
At 01:50 07/10/2004, you wrote:

Dear Jerry, Ram, and Jim,
Here are the profiles of zonally-averaged atmospheric temperature change that
you requested. As I mentioned in yesterday's email, I've prepared a couple of
different versions of these plots. First, there are two different analysis
periods: January 1979 through to December 1999, and January 1958 through to
December 1999. Second, temperature changes are expressed in two different ways:
in terms of linear trends per decade, and in terms of the total linear changes
over the two analysis period. So there are four different vertical profile
plots:
-rw-r--r-- 1 bsanter climate 194436 Oct 6 16:27 ccsp_vp_lt_1979-1999.ps
-rw-r--r-- 1 bsanter climate 142312 Oct 6 16:27 ccsp_vp_lt_1958-1999.ps
-rw-r--r-- 1 bsanter climate 201997 Oct 6 16:43 ccsp_vp_tlc_1958-1999.ps
-rw-r--r-- 1 bsanter climate 198109 Oct 6 17:04 ccsp_vp_tlc_1979-1999.ps
All the relevant information is encoded in the file name: "lt" denotes linear
trend, and "tlc" denotes total linear change. Personally, I have a preference
for the total linear change plots. If you compare panel f (the PCM ALL forcing
case) of the "tlc" plots for 1979-1999 and 1958-1999, the much larger total
changes over the longer analysis period are visually obvious. This is not the
case if changes are expressed in degrees C/decade.
I note that (as requested by Roger Pielke in Exeter), the plots are
appropriately area weighted.
All profiles of zonally-averaged atmospheric temperature change are ensemble
means. Each ensemble mean was calculated from four individual realizations.
There is no subtraction of control run drift, which probably is not a
significant factor at this point in the perturbation experiments.
I've also updated the two plots that I sent you yesterday, which show
global-mean and tropical-mean profiles of atmospheric temperature change. These
plots now include observed near-surface temperature trends, estimated from
HadCRUT2 and HadCRUTv (the latter is the variance corrected version of
HadCRUT2). PCM ALL and HadCRUT near-surface temperature changes are in good
agreement, both for global- and tropical averages. I'm pretty sure that in the
global-mean case, subsampling PCM ALL results with HadCRUT coverage would yield
a slightly warmer PCM ALL 2m temperature trend (in view of the muted warming of
2m temperatures at high southern latitudes in ALL; these areas are not well
sampled in HadCRUT).
It would be nice to show these plots of global- and tropical-average changes in
Chapter 5. I think they make some useful points.
Hope all of this is helpful,
With best regards,
Ben
(P.S.: I'd like to acknowledge the assistance of Charles Doutriaux and Mike
Wehner in producing these plots. Considerable data processing was involved in
generating these six figures).
--
----------------------------------------------------------------------------
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
----------------------------------------------------------------------------

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
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