date: Fri Sep 7 14:53:20 2001 from: Keith Briffa subject: Fwd: to: t.osborn@uea.ac.uk X-Sender: berninge@mm.mappi.helsinki.fi X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Fri, 07 Sep 2001 16:42:50 +0300 To: Keith Briffa , Frank.berninger@Helsinki.fi From: Frank Berninger Subject: Cc: John Grace 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]/