date: Fri, 27 May 2005 15:40:13 +0100 from: "Tett, Simon" subject: Paper to: t.osborn@uea.ac.uk Tim, Hi thanks very much. Quite interesting and I am happy to be a co-author. I think I would like to see a complete draft before making more comments though! Main comment -- can you be more quantitative i.e. use control data to compute uncertainties and then compare models with each other and the obs. I will write some text for the model description (I need to do it for Jason as well). The CET record is not good early on. I am not sure how to quantify this. Note that David Parker has a paper on uncertainty in CET. Models also likely to underestimate grid point var. I suspect the air temperature data is very poor nth of 70N and sth of 45S. Any way of including this in your analysis? Page 6, para 2. Note in HadCM3 there are quite strong changes in NH land snow cover due to trees being chopped down... I don't think solar var in ECHO-G is much greater than in HadCM3 -- see my last tech report. For your 50-year filter what are you doing for your last 25 years? (Mann, 2004 has some ideas). Simon Dr Simon Tett Managing Scientist, Data development and applications. Met Office Hadley Centre (Reading Unit) Meteorology Building, University of Reading, Reading RG6 6BB Tel: +44 (0)118 378 5614 Fax +44 (0)118 378 5615 Mobex: +44-(0)1392 886886 E-mail: simon.tett@metoffice.gov.uk http://www.metoffice.gov.uk Global climate data sets are available from http://www.hadobs.org