Saturday, March 17, 2012

2602.txt

cc: "'Brazdil Rudolf'" <brazdilatXYZxyzgr.muni.cz>, "'Petr Dobrovolny'" <dobro@ics.muni.cz>, <P.JonesatXYZxyz.ac.uk>
date: Tue, 17 Jun 2008 09:32:38 +0200
from: "Reinhard Boehm" <Reinhard.BoehmatXYZxyzg.ac.at>
subject: AW: AW: Central European temperature reconstruction
to: "'Anders Moberg'" <anders.mobergatXYZxyzgeo.su.se>, "'Reinhard Boehm'" <Reinhard.BoehmatXYZxyzg.ac.at>

Dear Anders, Rudolf and Petr,

First some additional information regarding Anders' questions:

Yes, everything is based on the only existing evidence of a multiyear
comparison between a preserved original early instrumental site and a modern
one. I would be happy if we could find additional information but it seems
that Kremsm�nster is unique (at least in the GAR I am quite sure about it).

The second thing we did was to develop two other "correction models" for NNW
and N-orientation (the Kremsm�nster EI-site Kremsm�nster is orientated
towards +30�. Yesterday's new version of the paper-draft tells you more
about that. It is quite a simple "model" but with the existing information
we cannot do better I believe.

Then we intensively studied metadata and could identify quite a lot of the
three relevant infos we needed for the majority of the EI-sites:
1) Height above ground (less important for EI-correction of monthly means as
argued in the paper draft, but interesting perhaps for future attempts on
daily extremes which should be more sensitive to this parameter
2) Orientation of the site. This allowed for allocating the single sites
(sunperiods) to one of the three correction models: -5 to +5� was defined to
be N-orientation model, <-5� to NNW and <+5�NNE
3) The contemporarily used algorithms for means calculation

You find the complete collection of metadata and the finally chosen
correction models on the attached xls-file

Finally (this is not yet written in the paper draft, but is implied in the
ppt-file through the Regensburg-example) we applied for those cases with
sufficient metadata information the individual correction models station by
station (and sometimes subperiod per subperiod, applied "estimated
correction models" in unsecure cases (e.g. based on the guess that similar
equipment and habits for means calculation ma be assumed in stations managed
by the same organisation or being in the same country. The remaining (few)
cased with insufficient information were at last adjusted to the regional
mean neighbouring ones with the usual proceeding when homogenising without
metadata.

Finally what we did not (could not) do was:

Accounting for different latitudes (within our region I believe this to be
of minor importance, so I would warn to overstreching the
Kremsm�nster-evidence too much, e.g. to the north (where insolation effects
maybe stronger in summer mornings and evenings) or to the south (where the
astronomical preliminaries tend to cause less problems, but maybe the
climatological ones (more sunshine in summer) tend to cause more)

Taking into account heat storage in the measuring walls when developing the
NNW- and th N-correction models. Also for this we did not really find the
necessary information on wall thicknesses, materials, colours etc...

All in all I think we have done a step into the right direction. You will
learn from the remaining part of the paper (I hope to be able to finish
soon, but there are also other obligations) that the resulting EI-corrected
records fit better to treering-reconstructions, have less difficulties to
explain the high glacier extensions in the Alps in the first part of 19th
century, reduce the previously existing strong difference of annual
temperature cycle between the 19th and the 20th century (this is one of
Phil's arguments in favour of doing the corrections), it is in better
agreement with some longterm historic model runs (RIC from the GKSS-people
for example) although the different solar forcing curves (mentioned in the
introduction)are ambiguous (Lean, 200 is in favour of a "cold version, Bard
et al., 2000) tells a story of quite strong solar forcing before the decline
in the 1910s). The high elevation ice cores from the Monte Rosa Region
(Colle Gnifetti)also provide two different informations, mineral dust
content tending towards a cooler (EI-corrected) version, stable isotopes
more towards a warmer one near 1800. The existing few infos on
high-elevation alpine lake sediments tend more to tell a story of warm
spring and summer temperatzures, but this is the only proxy-information
which really favours the warm solution without corrections. Not to forget at
last the "official" Central European CRU-version published in box 3.6, Fig.2
of WG1-2007 report which shows rather high EI-summer temperatures, just as
our own HISTALP series did before the EI correction.

SO if you ask me I am convinced that our new version of longterm temperature
records is nearer to the truth than the other existing ones without
EI-corrections. But I am not sure, whether we should extrapolate too much to
other regions. Series like Berlin or perhaps Paris should be the outermost
locations for it, Southern Sweden may need stronger corrections (as you have
already shown Anders), oceanic locations in UK maybe weaker ones and about
the south I am not sure which factor really dominates, the described
astronomical or the climatological influences. So I guess for the time being
we have a good solution for Central Europe, but we will have difficulties to
find quantitative information for other regions as long as the
"Kremsm�nsters" of the North, the West, the South and the East are not yet
existing. How about starting such comparative monitoring? Some of the
original EI-buildings should still exist.

OK, that�s all for the moment, I hope it provided the Millennium-group with
some useful facts for the decisions Anders was writing about.

Best regards

Reinhard

P.S.: I cc. this also to Phil, maybe ha also has some comments

-----Urspr�ngliche Nachricht-----
Von: Anders Moberg [mailto:anders.mobergatXYZxyzgeo.su.se]
Gesendet: Montag, 16. Juni 2008 23:34
An: Reinhard Boehm
Cc: 'Brazdil Rudolf'; Petr Dobrovolny
Betreff: Re: AW: Central European temperature reconstruction

Dear Reinhard,

cc. Rudolf and Petr

Thanks indeed for sending this information and corrected data. They come
very timely! I need not to say (as you already know it) that I consider
it to be very important that you have developed these corrected series.

I do understand that you will describe how you did the EI-corrections in
the paper. But can you tell us in a few sentences what it is based on?
By looking at your presentation (the pdf-file), I assume that your 8-yr
parallell observations in Kremsmuenster forms the basis for your
correction. Is this right? But how do you apply this knowledge to the
other stations? Does your correction model account for the orientation
(e.g. NE, NW, etc) of the thermometer-wall at each site? Do you account
for observation hours? Latitude? It would be good to get just some hints
of what you did.

I also have some comments that I would like address to Rudolf and Petr:
Given that this paper by Reinhard et al (as far as I understand) will be
the paper about long instrumental records in the CC special issue, it is
important that other related papers use the new homogenised series for
the sake of consistency. In particular, the paper about Central European
temperatures should be as consistent as possible with the new
EI-corrected data. We agreed some week ago to use a combination of
[Kremsmuenster+Basel+Prague+Rapp's German average] to construct the
instrumental regional average. As Reinhard now has developed homogenised
versions of both Kremsmuenster and Basel, we should use these new
versions. I assume that you can also use the new EI-corrected series in
your homogenisation of Prague. As concerns the Rapp series for Germany,
the situtation is more tricky. We could in principle consider using an
average of (some of) the German stations in Reinhard's dataset
(Hohenpeissenberg, Karlsruhe, Munchen, Regensburg, Stuttgart). But then
we would miss information from more northern parts of Germany. I
actually think it is more important to have the EI-corrected German
series from southen parts of Germany than having un-corrected Rapp data
for all Germany. We might consider some compromise? E.g. homogenising
the Rapp series with the EI-corrected German series as reference series.
Another thing; we could also consider using more station records from
Switzerland and Austria than only Basel and Kremsmuenster. I think we
should have a little email conversation about this, so that all of us
can say our opinions before we decide on how to construct an appropriate
Central European temperature series to be used for calibration of the
documentary data from CZ+DE+CH. What is your opinion -I mean all three
of you?

Regards,
Anders


Reinhard Boehm skrev:
> Dear Anders, dear Rudolf
>
> Please understand my delay in answering your questions and your data
> request. The reason war quite a complicated decision finding process
mainly
> with the Italian co-authors about our definite result in correcting the
> EI-bias in early warm-season temperatures.
> But last week we came to the decision about our definite new version of 32
> Central European temperature series starting before 1850.
> And I, as the lead-author finally decided to write the paper as part of
your
> planned Millennium-publication, Rudolf asked me to contribute to some time
> ago.
> So I have finally started writing and for Your information I attach the
> recent (yesterday's) status of the paper plus a presentation I gave about
it
> (see at pages 7 to 12 of the attached Mondsee-pdf).
> I also attach 2 xls-files. The first contains all 32 EI-series in the
region
> in three different modes: (from left to right) EI-corrected, homogenised
but
> not EI-corrected and the original series (only outlier corrected)
> The second xls-file explains the station code and it also tells you whom
you
> should acknowledge as data provider, if you explicitly use one of these
> series in the publication.
>
> Best regards
>
> Reinhard
>
> -----Urspr�ngliche Nachricht-----
> Von: Anders Moberg [mailto:anders.mobergatXYZxyzgeo.su.se]
> Gesendet: Mittwoch, 28. Mai 2008 11:38
> An: reinhard.boehmatXYZxyzg.ac.at; Dr. Ingeborg Auer
> Cc: Brazdil Rudolf; Petr Dobrovolny; Rob Wilson
> Betreff: Central European temperature reconstruction
>
> Dear Reinhard and Ingeborg,
>
> cc. Rudolf, Petr, Rob,
>
> Hope all is well with you! As you probably already know, I am working
> together with Rudolf, Petr, Rob and other colleagues in Millennium with
> writing papers for the Special Issue in Climatic Change that Rudolf is
> organizing. I have understood that Reinhard is contributing with a
> chapter about long instrumental records.
>
> One of the chapters will deal with reconstruction of monthly
> temperatures for Central Europe back to 1500, based on index series
> derived from documentary evidence from Germany, Switzerland and the
> Czech Republic. In the last few weeks, I have been engaged in the
> problem of calibrating these data against long instrumental data for
> Central Europe, and to put error bars on them. The basic principle for
> the calibration is simple linear regression for a period of overlapping
> data. The attached figure shows you some preliminary results for
> seasonal averages (month 13 = DJF, 14=MAM, 15=JJA, 16=SON). The error
> bars are 2*sigma error from calibration, with additional adjustment for
> changes in running correlations between the individual country series.
> (The error bar estimation for these data is far from trivial, but this
> is not what this email is about ...)
>
> So far, the instrumental data I used are taken from the CRUTEM2v
> dataset, with an extension back to 1781. Phil Jones and I created a long
> record for Central Europe (CE) from these data, for a paper we published
> in 2003. I use the same series here. However, we are discussing if we
> should rather use another average temperature series for CE which we
> develop specifially for this paper. This is the real reason for writing
> to you: We would need the best available long instrumental records from
> Germany, Switzerland and the Czech Republic to construct a suitable CE
> series. Would you be interested in contributing with a selection of
> series from HISTALP? Data from Austria can also be considered, even if
> no documentary data from your country are used, because Austria fits
> well into the climatic region of interest.
>
> We are of course aware of the problem of possible too warm summer
> temperatures before mid-19th century. As you can see in the attached
> plot, the reconstructed (smoothed) JJA temperatures lie consistently
> above the zero line (1961-90 average). Obviously, if the instrumental
> temperatures are biased in the calibration period (1781-1820), then the
> entire reconstruction will also be biased.
>
> If you have any instrumental series in the pipeline that are corrected
> for this bias, then it would be excellent if we could use them. Maybe
> you are planning to present such series in your chapter of the Special
> Issue?? If so, it would be a very nice connection between the two
> papers, if we can use the same data.
>
> If you don't have any such corrected data, then we can at least point
> out the problem and discuss it properly. In any case, we feel that it
> would be good to build a new instrumental CE temperature series, to be
> used here rather than the extended CRUTEM series. Many early data
> records in the CRUTEM dataset have not been subject to homogeneity
> testing. Rather, the dataset is just a collection of what Phil has been
> able to collect. (For example, it contains Austrian series from ALOCLIM
> and data from IMPROVE, but there are also other more or less untested
> early data).
>
> We hope that you would like to collaborate by contributing with your
> most appropriately selected station records. If you would like to do
> this, then we would need the data very soon as we are approaching the
> deadline for the paper and other chapters in the special issue are
> dependent on using our reconstruction. So, please, answer as soon as you
> can and tell us if, and how, you can contribute. I am convinced that
> Petr (who is the lead author) is happy to include you as co-author(s) if
> you like.
>
> Looking forward to hear from you soon,
>
> Best regards,
> Anders
>
>

--

Anders Moberg
Department of Physical Geography and Quaternary Geology
Stockholm University
SE-106 91 Stockholm
Sweden

Phone: +46 (0)8 6747814
Fax: +46 (0) 8 164818
www.ink.su.se
people.su.se/~amobe
anders.mobergatXYZxyzgeo.su.se

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