cc: david.easterling@noaa.gov, jay.lawrimore@noaa.gov, "Russell Vose" date: Wed Jul 13 09:52:28 2005 from: Phil Jones subject: Some more thoughts on DTR map for 1979-2004 to: "Byron Gleason" , Kevin Trenberth Kevin, Byron, Agree that we will have to wait till Russ gets back to check this out. Added Russ in on this reply. Russ sent Fig 3.2.2 for the ZOD, which we still have in the FOD figure at the moment. We will need this updating. Presumably the new one will be similar to one from the ZOD. That figure had a trend of -0.08 C/decade for 1950-2003. From a guesstimate of the trend over 1979-2003 in this figure, the trend is about -0.2 C in total. This sort of trend is in the first light blue category, just less than -0.1 C/decade. I reckon that the average of the trends in the 79-04 map would average to about this number. So, it seems OK. I am though a little alarmed at how variable the trends are between adjacent boxes. From knowledge of the likely variations in spatial density, most of these seem to occur where station numbers are likely low. Where density is high (US, Canada, northern/central Europe, northern Russia and China/Japan and eastern Australia) changes between adjacent boxes are a lot smoother. I also know that DTR amplifies any problem in station homogeneity (as opposed to the mean which reduces it). Problems are usually of the opposite sign for max and min. So, can you see if a similar plot for 1950-2004 would be better behaved. This period would be 55 years as opposed to 26. It could be that we might need to go to more than 18 years to get reliable trends for 1979-2004 - if you're using the same threshold as the mean temp maps. I have plans with Russ to look at these data for 1958-2001 and 1979-2001 with the ERA-40 Reanalyses (along with Adrian Simmons). ERA-40 should be good enough for the shorter period to assess reliability, but this will beyond the AR4. Cheers Phil At 21:39 12/07/2005, Byron Gleason wrote: Kevin, Russ Vose did the analysis and currently he is on vacation in Pennsylvania, and will return Monday. - Byron Kevin Trenberth wrote: Hi Byron Thanks for the figure. I have to express surprise over the figure. It shows a lot more red than I expected based on other material. Over the US Dai has produced DTR trends for a slightly different period: 1976-2004 and it is much bluer all round. I am also a bit alarmed at some spots where trends are opposite: 2 large positive spots near others of opposite sign. Is this consistent with Alexander et al 2005? Is this consistent with Fig 3.2.2. Kevin Byron Gleason wrote: Folks, Fig. 3.2.11 (global map 79-04 of dtr trends) now available on [1]ftp.ncdc.noaa.gov/pub/data/ipcc/ipcc05 This map was a little tricky style wise because it is temperature related so I wanted to use the same color scheme as the other temperature maps, however there isn't global coverage like the other temperature maps, thus the oceans end up being mostly grey. Nevertheless, I think it looks better than if I used the precip. color scheme (it would be a little atypical to depict temperature using green and tan). - Byron Phil Jones wrote: Dear All, I've picked up a file from Kevin where he has put all the new figures. Also downloaded them all myself, and have ben looking at them over a coffee for the last 10-15 minutes. Comments, thoughts under each variable. Temperature Maps The layout and grey/white are fine on these. The aim with the 1979-2004 ones is to have all 5 for this period with the same scale, which they do. As we are likely to get comments on these in this review round, I reckon the ones we currently have are fine. The annual plot for 79-04 will look a bit washed out cf 1901-2004, but it wouldn't if it was the DJF plot for the same period. So, I'm happy to go with these. Precipitation Maps These now have the better coverage (compared to the ZOD), so you've solved that issue. The problem with these plots is the two greys. There is a lot more little trend areas on these maps as opposed to the temperature ones. To be consistent with the temperature ones, I think we will have to go with the light grey for missing and white for little trend. There should only be a largish areas of white on the 79-04 annual map. There should be a lot less on the seasonal ones. Apologies for getting this wrong the other day. Can you make these changes to these 6? Finally The only other plots needed are the one for DTR (map will be 3.2.11, annual for 79-04, or whatever final year Russ is happy with) and a max/min/dtr annual series for the globe. Also there is the time series plots for precip, which Dave said all that was missing was the longer CRU series back to 1901. Thanks again for all your help with these figures. Thanks Jay for the details of how these have been produced. I'll use this to send Kevin some captions, if I get a chance today. Cheers Phil At 00:23 12/07/2005, Kevin Trenberth wrote: Thanks Byron I think I got them all. But have not looked at them: Phil I'll try to redo the Fig file tonite. Kevin Byron Gleason wrote: Folks, Figs (with new naming scheme) can now be found in: [2]ftp.ncdc.noaa.gov/pub/data/ipcc/ipcc05 Note: everything has been centered on 0.0 degrees and the tmean maps have been redone to account for a mistake where I was still saying "Grey Intervals" and it should have said "White Intervals". I will probably get a new ftp directory in the future, but for now this should suffice, and more maps to come tomorrow. - Byron Kevin Trenberth wrote: Hi all I have put the new figures into my file. I do note that 180 is in the center. For a lot of fields this is desirable because of the large effects of El Nino. But for land stuff it seems desirable to have the break elsewhere, perhaps with 0 meridian centered. I think this will be the case for precip, and so it probably should be for T too? It will mean we have a mixture in the chapter but that may be better that strict adherence to something that makes no sense in some cases. I am opening this up for your views. Kevin Byron Gleason wrote: -- **************** Kevin E. Trenberth e-mail: trenbert@ucar.edu Climate Analysis Section, NCAR [3]www.cgd.ucar.edu/cas/ P. O. Box 3000, (303) 497 1318 Boulder, CO 80307 (303) 497 1333 (fax) Street address: 1850 Table Mesa Drive, Boulder, CO 80303 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 ---------------------------------------------------------------------------- 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 ----------------------------------------------------------------------------