cc: Jonathan Overpeck <jto@u.arizona.edu>, Keith Briffa <k.briffa@uea.ac.uk>, Eystein Jansen <eystein.jansen@geo.uib.no>
date: Tue, 18 Jul 2006 14:45:32 +0200
from: Fortunat Joos <joos@climate.unibe.ch>
subject: Re: new fig 6.14
to: Tim Osborn <t.osborn@uea.ac.uk>

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Dear Tim,

Sorry, that was a very careless and a totally inappropriate choice of 
words. I seriously apologize. Of course smoothing is not dishonest (I do 
it also all the time). To the contrary, I very much apreciate all your 
hard work to do these figures. I know that it is very time consuming 
from own experience ... (that is perhaps why I did not reflect on my 
wording when writing the e-mail). What I wanted to say is that if one 
has the opportunity to show directly  what forcing was used by the model 
than I very much prefer to do so. I hope there remains no 
misunderstanding. I realize now that I should have used more modest 
wording at various places.

Let us see what Eystein, Peck and Keith are thinking about it.

With best wishes, Fortunat

Tim Osborn wrote:
> Hi all,
> 
> thanks for the responses, Peck and Fortunat.
> 
> I drafted the new figure 6.14 following as closely as possible the 
> approach used for the original forcing/simulation figure (now 6.13).  
> This is why I smoothed all series and used a common anomalisation period 
> for all curves across all panels.  It can greatly help to interpret why 
> the simulated temperature responds in the way it does, because the zero 
> (or "normal" level) is comparable across plots and because the strengths 
> of different forcings can be compared *on the same timescale* as the 
> simulated temperatures are shown.  And, for 6.13, with so many different 
> forcings and models shown, it would have been impossible to use 
> unsmoothed series without making the individual curves indistinguishable 
> (or indeed fitting them into such a compact figure).
> 
> Now that the EMIC panels are separate from the original 6.13, we do have 
> the opportunity to make different presentational choices.  But I think, 
> nevertheless, that some of the reasons for (i) proportional scaling, 
> (ii) common anomalisation period; and (iii) smoothing to achieve 
> presentation on comparable time scales, that held for 6.13 probably also 
> hold in 6.14.
> 
> However, I also appreciate the points raised by Fortunat, specifically 
> that (i) it is nice to be able to compare the magnitude of the 11-yr 
> solar cycles with the magnitude of the low-frequency solar variations; 
> and (ii) that using a modern reference period removes the interpretation 
> that we don't even know the forcing today.
> 
> So we have various advantages and disadvantages of different 
> presentational choices, and no set of choices will satisfy all these 
> competing demands.
> 
> One thing that I am particularly perturbed about is Fortunat's 
> implication that to show smoothed forcings would be scientifically 
> dishonest.  I disagree (and I was also upset by your choice of 
> wording).  If it were dishonest to show smoothed data, then presumably 
> the same holds for 6.13 (but its impossible to distinguish all the 
> different volcanic forcings if shown unsmoothed), but also to every 
> other graphic... should I be showing the EMIC simulated temperatures 
> without smoothing too, so you can see the individual yearly responses to 
> the volcanic spikes?  But annual means are formed from the temperatures 
> simulated on the model timesteps, so we still wouldn't be showing 
> results that had not been post-processed.  Most climate models, even 
> GCMs, respond in a quasi-linear way, such that the smoothed response to 
> unsmooth forcing is very similar to the response to smooth forcing.  So 
> if we are interested in the temperature response on time scales of 30 
> years and longer, it seems entirely appropriate (and better for 
> interpretation/comparison of forcings) to show the forcings on this time 
> scale too, because the forcing variations on those time scales are the 
> ones that are driving the temperature response (even though the forcing 
> may be intermittent like volcanoes or have 11-yr cycles like solar).
> 
> The choice of smoothing / no smoothing is not, therefore, anything to do 
> with honesty/dishonesty, but is purely a presentational choice that can 
> made accordingly to what the purpose of the figure is.  Here our purpose 
> seems to be long-term climate changes, rather than response to 
> individual volcanoes or to the 11-yr solar cycle.
> 
> So the position is:
> 
> (1) smoothing or no smoothing: there are arguments for both choices, 
> though clearly I prefer smoothing and Fortunat prefers no smoothing.  I 
> could make a figure which kept the smooth lines but put the raw annual 
> histogram volcanic spikes underneath in pale grey, as Peck requested 
> anyway (and possibly put the 11-yr solar cycles in pale brown underneath 
> the smoothed brown solar series).  This would be a compromise but the 
> main problem is that the scale of the largest volcanic spikes would far 
> exceed the scale I am using to show the smoothed series (so the panel is 
> not large enough to do this)!
> 
> (2) pre-industrial or present-day anomalisation reference period: again 
> there are arguments for both choices.  Whatever we choose, I firmly 
> believe it should be the same for *all* curves in this figure (which can 
> make a dramatic difference).
> 
> (3) exaggeration of solar scale or proportional vertical scales: this is 
> the one that I have the firmest opinion about.  I see no reason to 
> exaggerate the scale of the solar forcings relative to volcanic or 
> anthropogenic forcings.  The difference between the forcings looks clear 
> enough in the version of the figure that I made.  Exaggerating it will 
> wrongly make the Bard 2.5% case look (at first glance) bigger than the 
> anthropogenic forcing, and make it look more important than volcanic 
> forcing.
> 
> I'll hold off from making any more versions till decisions are made on 
> these issues.
> 
> Cheers
> 
> Tim
> 
> At 09:01 18/07/2006, Fortunat Joos wrote:
> 
>> 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.osborn@uea.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,
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