netcdf file with reduced gaussian grid

Remi Meynadier remi.meynadier at AERO.JUSSIEU.FR
Tue Mar 10 13:05:16 EDT 2009


Dear grads users,
I have a netcdf files (see the ncdump  below) with data defined on a reduced
gaussian grid (N256) and hybrid level for vertical resolution.
I can open it with sdfopen myfile.nc but it will only plot the first
vertical level (it works fine for the first level).
I need so to create a ddf file (see below) to force grads to take into the
vertical resolution.
But when i run the ddf file i have some trouble and it seems that grads does
not recognize the data.

Any clue where does it come from ?
Thanks in advance

Remi Meynadier

-----------------------------------------------------------------------
ddf file:
dset /homedata/meynadie/GRIB/ECMWF/divergence.nc
dtype netcdf
options yrev
undef -999
unpack scale_factor add_offset
title divergence model level GGR grid ECMWF
xdef 1024 linear 0 0.35156208
ydef 512 levels
-89.731150 -89.382870 -89.032540 -88.681750 -88.330770 -87.979720 -87.628610
-87.277480 -86.926320 -86.575150
-86.223980 -85.872790 -85.521600 -85.170410 -84.819210 -84.468010 -84.116810
-83.765600 -83.414400 -83.063190
-82.711980 -82.360770 -82.009560 -81.658350 -81.307140 -80.955930 -80.604710
-80.253500 -79.902290 -79.551070
-79.199860 -78.848640 -78.497430 -78.146210 -77.795000 -77.443780 -77.092560
-76.741350 -76.390130 -76.038910
-75.687700 -75.336480 -74.985260 -74.634050 -74.282830 -73.931610 -73.580400
-73.229180 -72.877960 -72.526740
-72.175520 -71.824310 -71.473090 -71.121870 -70.770650 -70.419440 -70.068220
-69.717000 -69.365780 -69.014560
-68.663340 -68.312130 -67.960910 -67.609690 -67.258470 -66.907250 -66.556030
-66.204820 -65.853600 -65.502380
-65.151160 -64.799940 -64.448720 -64.097500 -63.746290 -63.395070 -63.043850
-62.692630 -62.341410 -61.990190
-61.638970 -61.287760 -60.936540 -60.585320 -60.234100 -59.882880 -59.531660
-59.180440 -58.829220 -58.478000
-58.126790 -57.775570 -57.424350 -57.073130 -56.721910 -56.370690 -56.019470
-55.668250 -55.317030 -54.965810
-54.614600 -54.263380 -53.912160 -53.560940 -53.209720 -52.858500 -52.507280
-52.156060 -51.804840 -51.453620
-51.102410 -50.751190 -50.399970 -50.048750 -49.697530 -49.346310 -48.995090
-48.643870 -48.292650 -47.941430
-47.590210 -47.238990 -46.887780 -46.536560 -46.185340 -45.834120 -45.482900
-45.131680 -44.780460 -44.429240
-44.078020 -43.726800 -43.375580 -43.024360 -42.673150 -42.321930 -41.970710
-41.619490 -41.268270 -40.917050
-40.565830 -40.214610 -39.863390 -39.512170 -39.160950 -38.809730 -38.458510
-38.107300 -37.756080 -37.404860
-37.053640 -36.702420 -36.351200 -35.999980 -35.648760 -35.297540 -34.946320
-34.595100 -34.243880 -33.892660
-33.541450 -33.190230 -32.839010 -32.487790 -32.136570 -31.785350 -31.434130
-31.082910 -30.731690 -30.380470
-30.029250 -29.678030 -29.326810 -28.975590 -28.624380 -28.273160 -27.921940
-27.570720 -27.219500 -26.868280
-26.517060 -26.165840 -25.814620 -25.463400 -25.112180 -24.760960 -24.409740
-24.058520 -23.707310 -23.356090
-23.004870 -22.653650 -22.302430 -21.951210 -21.599990 -21.248770 -20.897550
-20.546330 -20.195110 -19.843890
-19.492670 -19.141450 -18.790230 -18.439020 -18.087800 -17.736580 -17.385360
-17.034140 -16.682920 -16.331700
-15.980480 -15.629260 -15.278040 -14.926820 -14.575600 -14.224380 -13.873160
-13.521940 -13.170730 -12.819510
-12.468290 -12.117070 -11.765850 -11.414630 -11.063410 -10.712190 -10.360970
-10.009750  -9.658530  -9.307310
-8.956090  -8.604870  -8.253650  -7.902440  -7.551220  -7.200000  -6.848780
 -6.497560  -6.146340  -5.795120
-5.443900  -5.092680  -4.741460  -4.390240  -4.039020  -3.687800  -3.336580
 -2.985360  -2.634150  -2.282930
-1.931710  -1.580490  -1.229270  -0.878050  -0.526830  -0.175610   0.175610
  0.526830   0.878050   1.229270
1.580490   1.931710   2.282930   2.634150   2.985360   3.336580   3.687800
 4.039020   4.390240   4.741460
5.092680   5.443900   5.795120   6.146340   6.497560   6.848780   7.200000
 7.551220   7.902440   8.253650
8.604870   8.956090   9.307310   9.658530  10.009750  10.360970  10.712190
11.063410  11.414630  11.765850
12.117070  12.468290  12.819510  13.170730  13.521940  13.873160  14.224380
 14.575600  14.926820  15.278040
15.629260  15.980480  16.331700  16.682920  17.034140  17.385360  17.736580
 18.087800  18.439020  18.790230
19.141450  19.492670  19.843890  20.195110  20.546330  20.897550  21.248770
 21.599990  21.951210  22.302430
22.653650  23.004870  23.356090  23.707310  24.058520  24.409740  24.760960
 25.112180  25.463400  25.814620
26.165840  26.517060  26.868280  27.219500  27.570720  27.921940  28.273160
 28.624380  28.975590  29.326810
29.678030  30.029250  30.380470  30.731690  31.082910  31.434130  31.785350
 32.136570  32.487790  32.839010
33.190230  33.541450  33.892660  34.243880  34.595100  34.946320  35.297540
 35.648760  35.999980  36.351200
36.702420  37.053640  37.404860  37.756080  38.107300  38.458510  38.809730
 39.160950  39.512170  39.863390
40.214610  40.565830  40.917050  41.268270  41.619490  41.970710  42.321930
 42.673150  43.024360  43.375580
43.726800  44.078020  44.429240  44.780460  45.131680  45.482900  45.834120
 46.185340  46.536560  46.887780
47.238990  47.590210  47.941430  48.292650  48.643870  48.995090  49.346310
 49.697530  50.048750  50.399970
50.751190  51.102410  51.453620  51.804840  52.156060  52.507280  52.858500
 53.209720  53.560940  53.912160
54.263380  54.614600  54.965810  55.317030  55.668250  56.019470  56.370690
 56.721910  57.073130  57.424350
57.775570  58.126790  58.478000  58.829220  59.180440  59.531660  59.882880
 60.234100  60.585320  60.936540
61.287760  61.638970  61.990190  62.341410  62.692630  63.043850  63.395070
 63.746290  64.097500  64.448720
64.799940  65.151160  65.502380  65.853600  66.204820  66.556030  66.907250
 67.258470  67.609690  67.960910
68.312130  68.663340  69.014560  69.365780  69.717000  70.068220  70.419440
 70.770650  71.121870  71.473090
71.824310  72.175520  72.526740  72.877960  73.229180  73.580400  73.931610
 74.282830  74.634050  74.985260
75.336480  75.687700  76.038910  76.390130  76.741350  77.092560  77.443780
 77.795000  78.146210  78.497430
78.848640  79.199860  79.551070  79.902290  80.253500  80.604710  80.955930
 81.307140  81.658350  82.009560
82.360770  82.711980  83.063190  83.414400  83.765600  84.116810  84.468010
 84.819210  85.170410  85.521600
85.872790  86.223980  86.575150  86.926320  87.277480  87.628610  87.979720
 88.330770  88.681750  89.032540
89.382870  89.731150
zdef 91 linear 1 1
tdef 4 linear 00z01may2006 6hr
vars 1
d_gds4_hybl=>div 91 t,z,y,x divergence model level ECMWF
endvars



ncdump -h divergence.nc
!ncdump -h divergence.nc6 , 3.110836e-06 ,
netcdf divergence {
dimensions:
        initial_time0_hours = 4 ;
        lv_HYBL1 = 91 ;
        lv_HYBL_i2 = 92 ;
        g4_lat_4 = 512 ;
        g4_lon_5 = 1024 ;

variables:
        long lv_HYBL1(lv_HYBL1) ;
                lv_HYBL1:units = "number" ;
                lv_HYBL1:long_name = "Hybrid level" ;
                lv_HYBL1:standard_name = "atmosphere hybrid sigma pressure
coordinate"
;
                lv_HYBL1:formula_terms = "a: lv_HYBL1_a b: lv_HYBL1_b ps:
unknown p0: P
0" ;
        float lv_HYBL1_a(lv_HYBL1) ;
                lv_HYBL1_a:long_name = "hybrid A coefficient at layer
midpoints" ;
                lv_HYBL1_a:note = "derived from lv_HYBL_i2_a as average of
layer interf
aces above and below midpoints" ;
        float lv_HYBL1_b(lv_HYBL1) ;
                lv_HYBL1_b:long_name = "hybrid B coefficient at layer
midpoints" ;
                lv_HYBL1_b:note = "derived from lv_HYBL_i2_b as average of
layer interf
aces above and below midpoints" ;
        float lv_HYBL_i2_a(lv_HYBL_i2) ;
                lv_HYBL_i2_a:long_name = "hybrid A coefficient at layer
interfaces" ;
                lv_HYBL_i2_a:note = "layer interfaces associated with hybrid
levels lv_
HYBL1" ;
        float lv_HYBL_i2_b(lv_HYBL_i2) ;
                lv_HYBL_i2_b:long_name = "hybrid B coefficient at layer
interfaces" ;
                lv_HYBL_i2_b:note = "layer interfaces associated with hybrid
levels lv_
HYBL1" ;
        float P0 ;
                P0:long_name = "reference pressure" ;
                P0:units = "Pa" ;
        float g4_lon_5(g4_lon_5) ;
                g4_lon_5:La1 = 89.731003f ;
                g4_lon_5:Lo1 = 0.f ;
                g4_lon_5:La2 = -89.731003f ;
                g4_lon_5:Lo2 = 359.64801f ;
                g4_lon_5:Di = 0.35156208f ;
                g4_lon_5:N = 256.f ;
                g4_lon_5:units = "degrees_east" ;
                g4_lon_5:GridType = "Gaussian Latitude/Longitude Grid" ;
                g4_lon_5:long_name = "longitude" ;
        float g4_lat_4(g4_lat_4) ;
                g4_lat_4:La1 = 89.731003f ;
                g4_lat_4:Lo1 = 0.f ;
                g4_lat_4:La2 = -89.731003f ;
                g4_lat_4:Lo2 = 359.64801f ;
                g4_lat_4:Di = 0.35156208f ;
                g4_lat_4:N = 256.f ;
                g4_lat_4:units = "degrees_north" ;
                g4_lat_4:GridType = "Gaussian Latitude/Longitude Grid" ;
                g4_lat_4:long_name = "latitude" ;
        double initial_time0_encoded(initial_time0_hours) ;
                initial_time0_encoded:units = "yyyymmddhh.hh_frac" ;
                initial_time0_encoded:long_name = "initial time encoded as
double" ;
        double initial_time0_hours(initial_time0_hours) ;
                initial_time0_hours:units = "hours since 1800-01-01 00:00" ;
                initial_time0_hours:long_name = "initial time" ;
        float D_GDS4_HYBL(initial_time0_hours, lv_HYBL1, g4_lat_4, g4_lon_5) ;
                D_GDS4_HYBL:forecast_time = 0 ;
                D_GDS4_HYBL:parameter_number = 155 ;
                D_GDS4_HYBL:parameter_table_version = 128 ;
                D_GDS4_HYBL:gds_grid_type = 4 ;
                D_GDS4_HYBL:level_indicator = 109 ;
                D_GDS4_HYBL:_FillValue = -999.f ;
                D_GDS4_HYBL:units = "s**-1" ;
                D_GDS4_HYBL:long_name = "Divergence" ;
                D_GDS4_HYBL:center = "European Center for Medium-Range
Weather Forecast
s - Reading" ;

// global attributes:
                :creation_date = "mar mar 10 10:31:19 CET 2009" ;
                :NCL_Version = "4.2.0.a034" ;
                :system = "Linux camelot.ipsl.polytechnique.fr
2.6.9-67.0.7.EL_lustre.1
                .6.5.1smp #1 SMP Wed Jun 18 19:11:05 EDT 2008 x86_64 x86_64
x86_64 GNU/Linux" ;
                :conventions = "None" ;
                :grib_source = "divergence.grib" ;
                :title = "NCL: convert-GRIB-to-netCDF" ;



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