cc: Byron Gleason <Byron.Gleason@noaa.gov>, david.easterling@noaa.gov, jay.lawrimore@noaa.gov, Russell Vose <Russell.Vose@noaa.gov>, Aiguo Dai <adai@cgd.ucar.edu>, Lisa Alexander <l.alexander@bom.gov.au>, David Parker <david.parker@metoffice.com>
date: Thu Jul 14 16:48:04 2005
from: Phil Jones <p.jones@uea.ac.uk>
subject: Re: Some more thoughts on DTR map for 1979-2004
to: Kevin Trenberth <trenbert@ucar.edu>

    Kevin,
       I've asked Lisa to produce a plot for 1979-2003 so we might get that tomorrow.  I was
    going to suggest we look at the CRU data but Aiguo has used that to some extent.
    As Spain was so different in the two maps, I've sent an email there for the definitive
    answer. I'm involved in a paper on this work, so asked for the trends over the 2 periods.
       I'll study them all - including Jay's tonight.
       Aiguo's grid looks as though it could degraded to Russ's. Not sure if Lisa's could
    be made available in a grid form - maybe at the HC model grid. If we got these
    we could then look at spatial correlations.
       Need to check what the threshold for years acceptable is first. Russ's should be the 18
    that Byron used for the 1979-2004 mean temp maps.  The other way to check
    Russ's is to average max and min and then compare with the mean trend map
    for the year for 1979-2004 - and similarly for the others.  We have some more confidence
    in that field.
    Cheers
    Phil

   At 15:57 14/07/2005, Kevin Trenberth wrote:

     Hi all
     I am attaching some figures from Aiguo Dai.  These include the trends in DTR, clouds and
     precip for 1050-2004 and 1979-2004.   He has also produced a number of other figures,
     such as correlations among these fields: DTR mostlt negatively correlated with cloud
     (exception Africa), cloud strong positive correlation with cloud everywhere.
     For convenience I am attaching the other ones as well.
     Notes from Dai:   The precip is from Chen et al. (2002 and updates). The merged DTR and
     cloud cover were
     derived from CRU_TS_2.02 and my synoptic obs.  based on  which  data set had better
     sampling
     (i.e., larger number of reports or stations for the CRU case) for each individual
     monthly/season at each
     grid box and a common/overlapping period was used to adjust the two data sets to have
     the same mean.
     This is a preliminary analysis that will be explored more as part of my NOAA proposal.
     ASOS cloud data
     since 1994 for N.A. were not used and U.S. military cloud data were included.
     ====
     Firstly for 1950-2004 there seems to be a very good agreement with Lisa's map thru 2003
     except Aiguo has Australia, Africa, S America and other areas also filled in.
     However for 1979-2004 there are major differences with the Vose one from NCDC.  South
     America still has negative trends in the Dai work vs positive for Vose. The US,
     Australia and Europe have distinctly more negative trends in Dai: the sign changes in
     many points.  In Spain it goes the other way?   There seems to be some agreement at some
     islands where presumably the data are limited and more likely similar: Hawaii, Bermuda,
     near Madagascar,??   The lack of reproducibility here is very disturbing.   Lisa can
     weigh in on which, if any is closest to hers.
     Comments?  Suggestions?
     Kevin
     Kevin Trenberth wrote:

     Hi all
     I  am sufficiently concerned about this that I have asked Aiguo Dai to use his data to
     compute DTR trends for 1979 to 2004.  Aiguo has all the synops and so values are based
     on a much more comprehensive dataset with wider coverage, including oceans, but perhaps
     with problems and inhomogeneities such as ASOS.  Still it will be a useful sanity check.
     Kevin
     Phil Jones wrote:

      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
     ----------------------------------------------------------------------------


     --
     ****************
     Kevin E. Trenberth                              e-mail: trenbert@ucar.edu
     Climate Analysis Section, NCAR                  [4]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
   ----------------------------------------------------------------------------

