Tuesday, May 15, 2012

4262.txt

cc: Susan Solomon <Susan.SolomonatXYZxyza.gov>, John Lanzante <John.LanzanteatXYZxyza.gov>, Melissa Free <melissa.free@noaa.gov>,Dian Seidel <dian.seidelatXYZxyza.gov>, Tom Wigley <wigley@cgd.ucar.edu>,Karl Taylor <taylor13atXYZxyzl.gov>, Thomas R Karl <Thomas.R.Karl@noaa.gov>,Carl Mears <mearsatXYZxyzss.com>, "David C. Bader" <bader2atXYZxyzl.gov>, "'Francis W. Zwiers'" <francis.zwiersatXYZxyzgc.ca>, Frank Wentz <frank.wentzatXYZxyzss.com>, Leopold Haimberger <leopold.haimbergeratXYZxyzvie.ac.at>, "Michael C. MacCracken" <mmaccracatXYZxyzcast.net>, Phil Jones <p.jonesatXYZxyz.ac.uk>, Steve Sherwood <Steven.SherwoodatXYZxyze.edu>, Tim Osborn <t.osborn@uea.ac.uk>,Gavin Schmidt <gschmidtatXYZxyzs.nasa.gov>, "Hack, James J." <jhackatXYZxyzl.gov>
date: Thu, 17 Jan 2008 14:17:59 -0800
from: Stephen Klein <klein21atXYZxyzl.gov>
subject: Re: The minus 1 (.png or .ps.gz)
to: Peter Thorne <peter.thorneatXYZxyzoffice.gov.uk>, Ben Santer <santer1atXYZxyzl.gov>

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Peter et al.,

Thanks for this figure updating Santer et al. 2005. Although I am a
bit rusty on this subject, there are two questions I have:

1) Does anybody have an explanation why there is a relative minimum
(and some negative trends) between 500 and 700 hPa? No models with
significant surface warming do this, and I can't think of a plausible
physical reason for this. Do people feel the relative cooling of this
layer relative to the surface is robust?

2) Have you thought of producing a comparison of models to radiosonde
observations for a longer term trend (late 1950s to 1999)? My
recollection (from when I worked with John L. and Dian S.) is that
the tropical radiosonde upper troposphere temperature trends were a
bit stronger over the longer-term. Even if you add this to the paper,
it might be nice to examine a figure of this type for the longer
period to assess models, and perhaps comment on in the paper.

Steve

At 02:56 AM 1/17/2008, Peter Thorne wrote:
>First hack at a caption:
>
>Figure 6. Tropical trends from all available radiosonde products for
>1979-1999. Trends have been calculated by zonally averaging the gridded
>data; applying a cos(lat) weighting to this zonal profile over 20N to
>20S to create a tropical mean timeseries; and then calculating a trend
>from this timeseries using a median of pairwise slope estimator that is
>robust to outliers (Lanzante, 1996). For RATPAC-A, which consists of a
>much sparser network, the tropical mean timeseries available from their
>website has been used to calculate the trend. Also shown are theoretical
>expectations based upon the assumption that the tropical troposphere
>behaves as a moist adiabat and climate model mean and 2 sigma estimates
>as to what the true trend should be. Both these estimates are derived
>from Figure 3 B of Santer et al. (2005), scaled by the available surface
>estimates (taken from Santer et al., 2006). The implicit assumption is
>made that these estimates adequately portray the real surface changes.
>
>I'm away Friday and Monday so will look afresh based upon accrued
>comments on Tuesday and make any mods then.
>
>My thanks to Leo for all of his hard work to provide the RAOBCORE
>products to me to calculate the trend values for this figure. And my
>apologies that my temperamental computer served to delay this by 24
>hours ... (don't ask!)
>
>Peter
>--
>Peter Thorne Climate Research Scientist
>Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB
>tel. +44 1392 886552 fax +44 1392 885681
>www.metoffice.gov.uk/hadobs
>
>

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