cc: Kevin Trenberth , Byron Gleason , david.easterling@noaa.gov date: Wed Jul 13 11:40:45 2005 from: Phil Jones subject: Re: tmean pics to: "Jay Lawrimore" 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 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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 ----------------------------------------------------------------------------