Wednesday, April 25, 2012

3507.txt

cc: Jonathan Overpeck <jtoatXYZxyzrizona.edu>, Keith Briffa <k.briffaatXYZxyz.ac.uk>, Eystein Jansen <eystein.jansenatXYZxyz.uib.no>
date: Tue, 18 Jul 2006 10:01:32 +0200
from: Fortunat Joos <joosatXYZxyzmate.unibe.ch>
subject: Re: new fig 6.14
to: Tim Osborn <t.osbornatXYZxyz.ac.uk>

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Hi Tim and co,

Thanks for the figure. I like the figure showing the model results and
the general outline/graphic style.

However, I am concerned about what is shown in the forcing figure.

1) Volcanic panel: I strongly believe that we should show what was used
by the model and not some 40 year smoothed curves for volcanic forcing
or any other forcing. So please use the original data file. Scientific
honesty demands to show what was used and not something post-processed.

2) solar panel:
2a) We must show the Wang-Lean-Shirley data on the original resolution
as used to drive the models. In this way, we also illustrate the
magnitude of the 11-yr annual cycle in comparison with the background
trend. The record being flat, apart from the 11-yr cycle, during the
last decades is a reality.
2b) Do not apply any smooting to the Bard data. Just use them as they
are and how they were published by Bard and used in the model.
2c) It is fine to supress the Bard 0.08 case after 1610 (not done in my
figure version)
2d) the emphasis of the figure is on the solar forcing differences. So,
please show solar somewhat overproportional in comparison to volcanic
and other forcings.

3) other forcings: again no smoothing needed here. It would be hard to
defend a double smoothing.

4)- normalisation of solar forcing to some period mean. If the different
solar forcings disagree for today as in your option, we may send the
signal that we do not even know solar forcing today.
Thus, I slightly prefer to have the same mean forcing values for all
solar records during the last few decades as shown in the attached
version. However, I also can see some arguments for other normalisations.

To illustrate points 1 to 4, I have prepared and attached a version of
the forcing panel.

other points

- Your choice of colors is fine
- time range 1000-2000 AD is fine
- suggest to remove the text from the y-labels except the units W/m2.

Sorry for this additional comments coming a bit late. However, I did not
realise that you planned to smoothed the model input data in any way.

With best wishes,

Fortunat

Tim Osborn wrote:
> Hi Peck, Eystein and Fortunat,
>
> I've drafted two versions of the new fig 6.14, comprising a new panel
> showing the forcing used in the EMIC runs, plus the old fig 6.13e panel
> showing the EMIC simulated NH temperatures. Keith has seen them already.
>
> First you should know what I did, so that you (especially Fortunat) can
> check that what I did was appropriate:
>
> (1) For the volcanic forcing, I simply took the volcanic RF forcing from
> Fortunat's file and applied the 30-year smoothing before plotting it.
>
> (2) For the solar forcing there are 2 curves. For the first, I took the
> Bard 0.25% column from Fortunat's RF file. For the second, I took the
> Bard 0.08% column from Fortunat's RF file from 1001 to 1609, and then
> appended the WLS RF forcing from 1610 to 1998. Then I smoothed the
> combined record. NOTE that for the Bard0.25%, the line is flat from
> 1961 onwards which probably isn't realistic, even though that is what
> was used in the model runs.
>
> (3) For the "all other forcings" there are 2 curves. For the first, I
> took the CO2 concentrations provided by Fortunat, then used the
> "standard" IPCC formula from the TAR (in fact the first of the three
> options for CO2 in IPCC TAR Table 6.2) to convert this to a radiative
> forcing. I then added this to the non-CO2 radiative forcings data from
> Fortunat's file, to get the total radiative forcing. For the second, I
> replaced all values after 1765 with the 1765 value (for the natural
> forcings case). Then I smoothed the combined record (as in fig 6.13c, I
> only applied a 10-year smoothing when plotting the "all other forcings",
> because it is fairly smooth anyway and using a high smoothing results in
> lower final values when there is a strong trend at the end of a time
> series).
>
> Now, some comments on the figures themselves (please print them and
> refer to them when reading this):
>
> (1) File 'chap6_f6.14_option1.pdf' is strongly preferred by Keith and
> me. This shows the three forcing components separately, which helps
> with understanding the individual causes of specific warming and cooling
> periods. I have managed to reduce the size of this considerably,
> compared to the equivalent panel in fig 6.13, because with only a few
> series on it I could squeeze them together more and also reduce the
> range of the vertical axes.
>
> (2) Although we don't prefer it, I have also made
> 'chap6_f6.14_option2.pdf' which is even smaller by only showing the sum
> of all the forcings in the top panel.
>
> Which version do you prefer? Please let me know so I can make final
> changes only to the preferred version.
>
> Some more comments:
>
> (1) Fig 6.14b was originally Fig 6.13e. When it was part of that
> figure, the colour bar showing the shades of grey used to depict the
> overlapping ranges of the published temperature reconstructions was only
> on Fig 6.13d. Do you think I should now also add it to the EMIC panel
> (6.14b), now that it is in a separate figure? It will be a bit of a
> squeeze because of the legend that is already in 6.14b.
>
> (2) Another carry over from when 6.14b was part of 6.13, is that the
> time range of all panels had to match (900-2010). Now that the EMICs
> are in a separate figure, I could start them in year 1000, which is when
> the forcing and simulations begin. Unless you want 6.13 and 6.14 to
> remain comparable? Again please comment/decide.
>
> (3) I wasn't sure what colours to use for the forcing series. In option
> 1, the volcanic and other forcings apply to all runs, so I chose black
> (with thick/thin used to distinguish the "all" forcings from the
> "natural-only" forcings (basically the thin flat line in "all other
> forcings). The cyan-green-blue runs used strong solar forcing, so I
> used blue for that forcing. The red-orange-brown runs used weak solar
> forcing, so I used brown for that forcing. Sound ok?
>
> Sorry for the long email, but I wanted to get everything explained to
> avoid too many iterations.
>
> Please let me know your decisions/comments on these questions, or on any
> other aspects of the new figure.
>
> Cheers
>
> Tim
> Dr Timothy J Osborn, Academic Fellow
> Climatic Research Unit
> School of Environmental Sciences, University of East Anglia
> Norwich NR4 7TJ, UK
>
> e-mail: t.osbornatXYZxyz.ac.uk
> phone: +44 1603 592089
> fax: +44 1603 507784
> web: http://www.cru.uea.ac.uk/~timo/
> sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm
>
> **Norwich -- City for Science:
> **Hosting the BA Festival 2-9 September 2006

--

Climate and Environmental Physics,
Physics Institute, University of Bern
Sidlerstr. 5, CH-3012 Bern
Phone: ++41(0)31 631 44 61 Fax: ++41(0)31 631 87 42
Internet: http://www.climate.unibe.ch/~joos/


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