date: Mon Jul 13 15:22:10 2009 from: Tim Osborn subject: Re: cruts tmp to 2008 to: Ian Harris Negative spikes fixed (see e.g. Mali on page 12 of new attachment). Mean differences slightly improved, though not much. BTW attachment shows last year's CRUTS3 in black and the latest in pink. I haven't (yet) compared the 1961-1990 mean of last year's and latest CRUTS3 with the correct normals from New et al. It might be that the latest version is the better. I'll do that next! Tim At 10:30 13/07/2009, you wrote: Hi Tim, A new cru_ts_3_00.1901.2008.tmp.dat.nc.gzis now in /cru/cruts/ It should fix the negative excessions, and I have a hunch that it might fix the means too. You see, I noticed that the mean differences were all negative.. you can probably guess the rest, given the other fixes I've just made! Cheers Harry On 10 Jul 2009, at 10:55, Ian Harris wrote: Hi Tim, A slightly more in depth reply ;) On 10 Jul 2009, at 00:19, Tim Osborn wrote: Hi Harry, finally had time to take a look at the latest cruts3 run through to 2008 for tmp, picked up from /cru/cruts/ Two PDFs showing seasonal national means are attached. Look at ...2008a_vs_2008b.pdf first. Black is your previous update to 2008, pink is the latest one. Many very similar, some small differences (presumably due to outlier 3/4 SD removal... note that as these are national/seasonal means, outliers might be quite large, yet only show up small in the means if many other stations contribute). Yup, as in the Mexico/Guatemala spike: page 4. The hot spike in Guatemala SON has been removed in the new version. That looks much better. page 6 & page 9: the hot spikes in France, Italy and Austria in JJA in 2003 have been reduce slightly too. Not sure if this is right or not, could ask Phil what he thinks. Could Jul & Aug 2003 have been so hot that some observations validly did exceed the +3SD outlier check? Or do you use a +4SD check for TMP? Anyway, this is one to ask Phil about. Nope, 4SD is for precip only. There are various other erroneous hot spikes that have now been correctly removed, I won't list them all here. However, there are some cold spikes in both previous and latest 2008 updates... see e.g. Mali SON on page 12. Have you turned on only outlier checking for +3SD, and not for -3SD? Some wrong-looking cold spikes are still present. Yes, **sigh** - abs() now included, re-running. Now look at ...2005_vs_2008b.pdf. Black is last years CRUTS3 through to 2005 (I know the files went to mid 2006, but I stopped at last complete year). Note this isn't CRUTS2.1! :-) Pink is again the newest version of the update to 2008. There are some early 20th century differences that I'm not too bothered about, though it would be nice to know why they arise. One concern is that the mean level is different between the versions... see e.g. JJA for various countries on pages 7 and 8. Seems to be a constant offset. It's too big to be a simple rounding error in my calculations (I may have changed from 1 dec. place to 2 dec. place, but some differences are about 0.5 deg C), and these are absolute values so there's no dependency on any anomalisation/reference period meaning as I'm not doing any. Intriguing. Perhaps some normals have change in some regions/ seasons? It's very worrying, as they really should be ~identical! Normals are read from the original (sacrosanct) climatology files so they shouldn't have changed at all. The gridding, etc are the same, too. I will try running old and new anomaly programs to compare outputs.. So: (1) hot spikes have been corrected. (2) cold spikes still there. (3) some odd differences in mean level. Progress! Of the seemingly-endless kind. Cheers for your help with this. Harry Ian "Harry" Harris Climatic Research Unit School of Environmental Sciences University of East Anglia Norwich NR4 7TJ United Kingdom