cc: Kevin Trenberth <trenbert@ucar.edu>, Byron Gleason <Byron.Gleason@noaa.gov>, david.easterling@noaa.gov
date: Wed Jul 13 11:40:45 2005
from: Phil Jones <p.jones@uea.ac.uk>
subject: Re: tmean pics
to: "Jay Lawrimore" <Jay.Lawrimore@noaa.gov>

    Jay,
       Well spotted !  There is something on our web site about this - somewhat hidden
    under our high-resolution datasets. So well hidden that I can't find it ! The original
    reason for developing these high-resolution datasets was to have them globally
    complete for 1901-2000 for the world's land areas (except Antarctica). This was for
    driving vegetation models. They still are used for this, but they have been used for
    much more. To make them complete, we interpolate the anomaly fields (there is
    a little more in this latest paper attached). How good this works is obviously variable
    dependent. It is the largest problem with precipitation as this has the shortest
    correlation length scales.
       So, this problem is the same as you have (Smith and Reynolds, most recently) when
    grids are infilled, which in anomaly form relax to zero (the average value of the1961-90
    period is zero). This is why the SR averages for infilled datasets are 0.1-0.2C warmer
    in the pre-1920 period than non-infilled ones. The same thing happens with RSOI
    techniques. Kevin and Jim Hurrell have a paper on this wrt SST.
       Without infilling the number of boxes decreases in earlier years, so you are
    essentially assuming the average of the missing boxes is equal to those that exist.
    With infilling you give them zero or near zero, which wrt 1961-90 makes them warmer
    for early decades in the 20th century.
       I say all this for temperature, as it is easy to follow. For precip the problem is
   greater
    in areal extent.  There is a field we have somewhere, which is the distance to the nearest
    real station (for each variable/date), which we have used to omit these points. However,
    for precip it makes very little difference.
       What I would do is just average what is there and see how much it differs from GHCN
    which will omit missing areas. As we're only showing CRU as a smoothed series, the fact
    that the individual years pre-1920 for CRU will be less variable than later will not be
    apparent.  There are loads of other problems, with both our dataset and GHCN (as gridded
    precip) which you alluded to in your email about the precip/temp maps. Some of these
    effects can be seen in the time series you've sent. There are more stations in this
    region of equatorial Pacific from the late 1950s to 1990.
       As our fields are complete (for land areas), you should be able to simply average them
   (with areal
    weighting) to derive a global land series. If you do take anomalies, take out the 1961-90
    one. A simple way to omit the areas infilled is to calculate the SD of the 12 months'
   anomalies
    for each year. If the number is zero or very small then omit that year.

       Hope this explains the issue.
    Cheers
    Phil
   At 17:29 12/07/2005, Jay Lawrimore wrote:

     Hi Phil,
     I'm working on the CRU time series with gridded data from 1901 to 2002. In running it
     through our station analysis system I've taken the half degree grids and assigned a
     lat/lon to each to create pseudo-stations. After running some analyses and looking back
     at the original data files that Byron downloaded from your ftp site - it appears there
     are lengthy periods when, instead of assigning missing values, the grids have been
     assigned climatological normals. For instance in the area 10N to 0N and 180W to 80W,
     there are 44 grid boxes with data and many of these appear to have normals from the
     early 1920s back to 1901.  This results in odd looking time series as you see in the
     attached.  Here are the data for 1 of the grids - taken from the file
     cru_ts_2_10.1901-2002.pre.  What are your thoughts on how this should be handled?  Jay
     Grid-ref= 190, 200
         0  104   42  600 2819 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2759 3082 2930 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2739 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2657 3082 3062 3263 4452 4047 1852  114
         0  103   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 3079 3082 3080 3263 4452 4047 1790  114
         0  104   42  600 2737 3082 3062 3054 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 3136 3082 3062 3263 4452 3999 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2737 3082 3062 3263 4452 3809 1852  111
         0  104   42  600 2737 3082 3062 3263 4452 4047 1852  114
         0  104   42  600 2953 3082 3062 3387 4612 4047 1852  114
         0  104   42  600 2737 3082 3062 3299 4452 4047 1852  114
         0  104   42  600 2737 3122 3062 3263 4452 4047 1852  114
         0  104   45  600 2542 3082 3062 3263 4452 4047 1852  114
         0  104   40  600 2537 3082 3062 3263 4452 4116 1852  114
         0  104   42  600 2737 3082 3062 3394 4452 3719 1852  114
         0   50   17  146 1771 2765 2728 2349 3330 4084 2503   74
         0   84   32  612 3144 2811 3117 3325 6174 4140 1296   32
         0  121   79  563 2791 2546 4109 3051 1798 1785  659  104
         0  155   30  316 2605 1902 2872 2405 2684 2076  604   38
         0  101   59  961 2603 2777 2397 3142 2880 2331  941   85
         0  121   76  859 3060 3258 2471 1596 3601 2048  794  124
         0  108   60  745 2329 2133 4461 4193 2391 2659  368   51
         0   87   50  589 3117 3584 7556 7832 5787 1562 1029   66
         0  184   52  841 3645 3757 2936 6490 4407 4553 2750   58
         0  143   44  377 3175 2638 3104 3831 4429 5897 1783  233
         0  127   73  762 3886 6198 2642 3126 3633 4990 1946   42
         0    4    2   30 4622 3097 4467 2013 9673 8641 2966  377
         0    5   10  164 4059 3332 1861 7992 8788 3517 2776    4
         0    4    0   24 1593 2872  585  199 2462 3594 4272  260
         6    7  145   17 1891 2765  707 1028 5747 6152 1100    5
         3    6    2  947 2211 2117 5416 1266 3775 2291 3557  238
         0  208  420  161 3035 2228 2847 3665 4772 5233 1726  543
         5    7  303 2247 3303 3769 2204 5006 7163 5059 6092  396
         5   27  157 1160 3842 4623 7081 7156 5524 3477 6016   29
         0    4    2  441 5186 2040 2719 4392 4127 2793 1640  133
         0    4    3   38 2425 1637 3013 3939 3503 4246 3164  573
         0    5   47  470 1122 3720 3270 2013 3517 3554 3742  564
        10  293   66   40 1773 2370 3328 1707 2813 3813 4031    8
         0    7    0   40 1190 3615 3208 4010 5164 2845   94  123
         0    7   30  109 2384 3067 2526 4053 3374 6929 1942  422
         0   10   12  528 3380 2302 4482 2059 5088 3715 1207    6
         0    8    0 1060 1891 3686 7443 3488 3975 2258 1526  140
         0    4    2   3010298 1880 2820 1586 4193 2570 2507  311
         0   16    2 1231 7299 4851 4084 2150 7034 8062  617   16
         7    7    0   81 1929 3970 6399 6732 8592 8916 1707  165
         4   75    3  209 2709 3686 1846 3120 5369 4282 2459    3
         0   17  495   64 3467 2308 3300 1547 3294 3222  194   21
         0    5   82  198 3125 4783 2461 2170 2889 2991 1422  156
         0    6    3   40 1010 2019  998 1341 4452 4800  511    4
         2    7  146 1977 2414 4087 3671 5554 4817 5176 2348    3
         0   28  131   85 1606 4219 5624 3247 3624 3566  950   97
         0   14   17 1527 2575 2971 2186 3648 1999 5075  585  231
         3    2   36 2180 2080 2962 3080 2173 3592 4468 3262    7
         0   13   25  965 2225 4984 3971 3048 3388 5589  941  112
         0    3    0   30 2638 1840  738 1609 5208 4747 3079  135
         0    3   74  448 5044 4349 2569 2718 3508 4557  517  117
         3  307   70 1923 1267 2950 3545 2578 5685 2271  567  433
         2    3  161  116 5134 4512 3925 2239 4167 4942 2407  241
         4    4    3  532 3361 2589 1246 3929 684710094 1994  316
         0   78  148 1302 2638 3698 6025 4223 4964 6751 1922    8
         0   13   69 1201 3320 2959 2810 3903 5885 6209 1918   20
         0    3   99  137 3388 3446 1350 2043 3152 1627 2050  197
         0    2    2  809 3437 4679 4350 5756 5315 4209 2146   17
         0    5    0 1143 3736 3609 1271 2180 7906 2611  228   19
         0   10    3   53 1330 1800 3368 2780 6410 3873 4012    7
         0  140    3  377 2022 4444 2936  679 4260 3594 1028    3
         0    3    2  490 2050 3165 2272 1883 3009 2602 1370    3
         0  149   40  239 5161 1168 4761 3965 4897 3153  578  300
         0    7    9 1511 3484 4318 3196 4053 7799 5533 1646  275
         5   56    0  428 3908 2644 2440 2075 5823 5035 3233   35
         0    7   33  361 4584 5030 3270 5068 3432 6625 1292  637
         2  120   16   56 7485 3014 2514 1344 4073 4003 1579   38
         0   94   98  250 1617 2672 2247 3234 4852 5792 3753  350
         0  442    0  398 2129 3134 2449 2855 5516 2161  705  115
         0   81    0  589 1623 2244 2532 3671 2649 4181 1113    4
         0    3    3   40 4891 4617 2780 2281 1714 2740  133  144
         0    7   35   78 1790 2019 3812 3071 3170 2404  468   18
         0  125   41  166 2417 2244 3046 6605 3650 7876  339   21
         2   70   26   32 2211 2798 2563 2118 3793 3728 2357  215
         2    7   53  834 3248 2422 3126 3426 3214 1085 3627   84
         0   72    2  240 1598 2315 3150 3430 2920 2667 1274  123
         0   84   15  355 1363 1963 4583 4082 5222 4517 1576  207
         0   30   23  643 2616 4447 3928 3906 4714 3477 1215   64
         0   26   33  464 2548 1560 2100 3341 3446 4161 1994   52
         0   13  173 1973 2811 2490 4060 5061 4185 5484 1542  135
         4   18   26  325 4943 2872 5462 3244 3726 3161 3129   21
         6   31   23 1261 1557 2712  848 2219 5422 2878 3990   29
         0   36   20  259 1426 3248 4078 3123 5360 5682 2248  237
         0  424    8  767 3005 3076 1375 3580 4438 2076 1276  147
         0   32   15  210 4195 2672 2097 1840 3673 2194 1840  108
         2   15   42  179 3300 1797 1748 1508 2524 3230 1711  123
         4   31   11  252 2356 2124 2189 1958 3944 3809 1783   62
     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:
     [1]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: [2]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    [4]p.jones@uea.ac.uk
     NR4 7TJ
     UK
     ----------------------------------------------------------------------------


     --
     Jay Lawrimore
     Chief, Climate Monitoring Branch
     NOAAs National Climatic Data Center
     Scientific Services Division
     Veach-Baley Federal Building
     151 Patton Avenue, Asheville, NC 28801-5001
     Ph. (828) 271-4750, Fax (828) 271-4328
     [5]Jay.Lawrimore@noaa.gov

     Visit the NCDC Monitoring Site:
     [6]http://www.ncdc.noaa.gov/oa/climate/research/monitoring.html

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

