date: Wed, 06 Nov 2002 14:25:58 -0700 from: "Dr. Jacek Majorowicz" subject: Re:Majorowicz view to: Tim Osborn Dear Sir: Thank you for your very interesting paper with Dr. Briffa. HC 2001 GRL paper makes an assumption in which the observational (etheo station's based) surface temperatures are part of their model.Their model used to fit temperature anomalies with depth conssists of the observational (metheorological stations) and pre-observational level which is the only freedom level in the model. Well temperature mathod can only show ground warming changes and this is sometimes different from the air surface temperature changes. This is especially the case when our well data come from the remote areas which went through land changes (clear cutting, changing of grass land to agriculture or grazing systems, forest fires etc plus changes in boundary conditions like moisture, snow etc). Staraight comparison of these with standard condition metheorological stations is therefore difficult or not correct. In fact some of the above conditions are likely the cause for ground surface temperature warming magnitudes in the last century to be higher than air surface temperature changes from metheorological stations. In many of my papers we showed that GST warming from wells is higher than SAT based warming from metheo stations . Therefore large warming change showed by HO 2001 is maybe a result of the above i.e. well reconstructions show higher groud surface warming than oservational air surface data in many areas consisting their well data basis. (see our Skinner and Majorowicz, Climate Research, v. 12, 39-52,1999 and my previous work in Clim. Change in 1977 (35, p. 485-500). Asuuming these as part of the ground surface temperature change model is therefore risky. I have attached very schematic figure (showed it in Nice at EGS 2002 at Mann's at al session) in which I compare Huang Pollack Shen (2000, v. 403. 17 February) northern hemisphere reconstruction from wells with Mann and Jones (lower) proxy reconstructions. Instead of using year 2000 as reference (as Huang et al in their Nature work) I am shifting their curve (based on well temperature reconstructions) to 1600hundreds level. Such relative change of levels sugest that if let's say Jones et al., level before major recent warming is correct, the well temperature reconstruction level is higher in the recent couple centuries and mainly in 20th century. This in fact is what I observe across Canada. My warming magnitudes for ground warming are higher than metheo observation. I realise that it is all relative where we put the level for comparison ., howeer, it leads to different interpretations. One can say that proxy data fail to show previous significant cooling before last century warming; I can say that well temperature based ground warming is higher than observations in recent years for the reasons as above. I hope this insight will be of interest. I am hoping to make it to EGS 2003 in Nice and hope to see you and have some discussions. Best regards Jacek Majorowicz Edmonton ----- Original Message ----- From: "Tim Osborn" To: "Dr. Jacek Majorowicz" Sent: Tuesday, November 05, 2002 7:49 AM Subject: Re: jgr reprint attached > At 17:33 02/11/02, you wrote: > >with best regards > >Majorowicz > >Edmonton > Thanks - looks very interesting. I attach one in return! > > Tim > > ---------------------------------------------------------------------------- ---- > Dr Timothy J Osborn | phone: +44 1603 592089 > Senior Research Associate | fax: +44 1603 507784 > Climatic Research Unit | e-mail: t.osborn@uea.ac.uk > School of Environmental Sciences | web-site: > University of East Anglia __________| http://www.cru.uea.ac.uk/~timo/ > Norwich NR4 7TJ | sunclock: > UK | http://www.cru.uea.ac.uk/~timo/sunclock.htm > Attachment Converted: "C:\EUDORA\Attach\fig0203E.pdf"