Monday, June 11, 2012

5108.txt

date: Fri Sep 7 14:53:20 2001
from: Keith Briffa <k.briffaatXYZxyz.ac.uk>
subject: Fwd:
to: t.osbornatXYZxyz.ac.uk

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Date: Fri, 07 Sep 2001 16:42:50 +0300
To: Keith Briffa <k.briffaatXYZxyz.ac.uk>, Frank.berninger@Helsinki.fi
From: Frank Berninger <Frank.BerningeratXYZxyzsinki.fi>
Subject:
Cc: John Grace <jgraceatXYZxyz0.bio.ed.ac.uk>
Dear Keith,
After our telephone discussion.
An additional remark: We will not only have to downscale the GCM.s but also upscale the
growth models. There are different schools for that and I am in the school that requires
less climate data to do the job.
If we look at GCM downscaling I think we will run on two levels:
I am not totally shure what to say about the GCM stuff.... On the one hand GCM:s are too
bad (=do not agree with each other sufficiently) to justify a complicated effort to
scale them down, on the other hand we would require weather data that is good enough (or
our model results will be flawed.... I am remembering with horror a project where
climate change was imposed on temperature but not absolute humdity and the trees got
unhappy in dry desert air....) So I would give your free hands to decide.
1) For a few sample sites (where models will be run at greater detail: Most models
require:
Temperature (i.e. daily max and min) , Irradiance, Air humidity, wind speed and
precipitation
For our systems the sensitivity to wind speed is very small. (i.e unless there are
dramatic changes predicted by GCM:s forget about it. Precipitation is probably not so
important on timberline.
The locations will be
3 Northern Scandinavia
1 Scottland
3 in the alps
1 in the Southern Apeninnes
1 in the Pyrenees
2) For the rest of the area probably changes in temperature and irradiance at the ground
on a monthly basis would be ok. (Depending on the upscaling scheme from the process
models). Precipitation in the mountains is tricky and models will not be very sensitive
to it.
Tree ring modelling:
I would like to see the work of Tom Melvin continued. I have made a trial to interpret
chronologies using a kind of limitation hypothesis and found interesting results (see
attachment (that is at the moment in the hands of a few referees of Nature). I think
that this could be associated with more long term modelling approaches (like the ones of
Tom) in different ways.,
I would try to phone you again (probably on wednesday thursday)
Frank
Frank Berninger
PhD, Docent
Department of Forest Ecology
POBOX 27
00014 University of Helsinki / Finland
Tel +358 9 191 58134
Fax + 358 9 191 58100

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784
[1]http://www.cru.uea.ac.uk/cru/people/briffa[2]/

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