cc: deparker@meto.gov.uk date: Thu Oct 19 15:27:53 2000 from: Phil Jones subject: Re: NATURE PAPER to: c.folland@niwa.cri.nz Chris, I don't think the method of calculating monthly mean temps has changed dramatically over the 20th century. English speaking countries tended to use the mean of min and max, while others used the means based on fixed hours. Canada, USA, India, Pakistan, Australia, NZ, Britain and South Africa and a few other countries have not changed at all. The difficulty will be finding enough data to assess what the uncertainties of the (max+min)/2 method are. To do this we'll need anomaly time series for both methods, hence my suggestion of using model runs. Only a few small countries have changed to (max+min)/2. In many others there seem to be a few climatologists who were listened to, who said there would be homogeneity problems if changes were made. Cheers Phil At 09:41 AM 10/19/00 +1300, c.folland@niwa.cri.nz wrote: >Phil > >I agree. There is a possible issue. If the balance of the methods of >calculating the average globally changed, or kept changing globally, >then a residual error or uncertainty would arise. Any thoughts? > >Weather here much better now so I may book up a trip for Saturday >to see the Kauri forests and the West Coast. > > >Chris > > > >On 18 Oct 2000, at 15:03, Phil Jones wrote: >