cc: Francis Zwiers date: Fri Oct 1 09:20:07 2004 from: Phil Jones subject: Re: Global warming to: "Fudge, Dennis WLAP:EX" Dennis, Hopefully you can read pdf files. The attachment and maybe some of the references in it will give you the answer to your question(s). Each station is in one of our grid cells (5 by 5 deg. of lat/long) and we use anomalies (departures) from the 1961-90 period (12 monthly averages for each station). Some boxes are based on many stations, some on just one. The paper refers to another in JGR from 2001 (Jones et al., 2001) that adjusts the variance of the series to account for differing station numbers over time. You can read a little more about this on our web site [1]http://www.cru.uea.ac.uk then go to data, then to temperature. There are a number of other FAQs there as well. We do a small amount of extrapolation - see the paper. I have cc'd this message to Francis Zwiers, who is the Canadian Govt scientist (at Victoria) you might like to contact for further info. He was involved in a project to adjust Canadian temperature data for many of the problems of site changes and observational practice changes that have occurred over the years. For Canada, we have incorporated this dataset. We try to include as much of this work as possible, but for a lot of countries we have to do this work ourselves. This is sub-optimal as we don't have all the necessary metadata (data about data), but we do the best we can. I will be travelling much of October, but if you have any additional questions email me. Francis is also likely travelling as well, but he should be also able to answer most questions. Cheers Phil At 18:38 28/09/2004, you wrote: I have been trying to find information of how the temperature trends are calculated. I have contacted several people from the Canadian Federal Government but no one was able to answer my question. I know the temperatures are average for each grid cells. But using just one grid cell as an example und using only land stations and ignoring the weighting applied; If there were 10 meteorological stations in that cell in 1970 and there are now 7 stations, are only those seven station used for every year? Or are all stations used when ever available? If all stations are used, is there an effort to extrapolate for the now none operational stations? Dennis Fudge Air Pollution Meteorologist Ministry of Water, Land and Air Protection 250-565-4210 If you woke up breathing, congratulations! You have another chance! Prof. Phil Jones Climatic Research Unit Telephone +44 (0) 1603 592090 School of Environmental Sciences Fax +44 (0) 1603 507784 University of East Anglia Norwich Email p.jones@uea.ac.uk NR4 7TJ UK ----------------------------------------------------------------------------