[gradsusr] 365_day_calendar & rotated_latitude_longitude grid mapping
Jennifer Adams
jma at cola.iges.org
Sun Feb 15 09:53:29 EST 2015
The grid is not rectilinear — the coordinates lat and lon are 2-dimensional variables, so GrADS will not handle this in its native format, unless you want to read it in on an abstract i,j grid and not use any mapping (‘set mproj off’). In that case, you would use:
xdef 194 linear 1 1
ydef 201 linear 1 1
The solution I use for files like this is to create a file that contains interpolation weights for use with a 'PDEF general’ entry. Some guidance and scripts for how to do this are in ftp://cola.gmu.edu/pub/jma/cmip5.
—Jennifer
On Feb 13, 2015, at 10:23 AM, Chao TANG <chao.tang.1 at gmail.com> wrote:
> Dear All,
>
>
> I have a problem to read netCDF data with 365_day_calendar & rotated_latitude_longitude grid mapping.
>
> I downloaded the data from esgf German dkrz portal, it’s the release data of RCA4 model in SMHI for Cordex Africa domain.
>
> As I know, a descriptor file is needed to read this netcdf file. I am using GrADS Version 2.0.2 on Mac OS 10.10.2.
>
> That’s the first descriptor file I have ever write.
>
> ===================================================
> dset ^tas_AFR-44_MOHC-HadGEM2-ES_historical_r1i1p1_SMHI-RCA4_v1_mon_200101-200512.nc
> dtype netcdf
> undef 1.e+20_FillValue
> options 365_day_calendar
> pdef 201 194 ROTLLR -180 90 0.44 0.44 -24.64 -45.76
> xdef 194 linear -24.64 0.44
> ydef 201 linear -45.76 0.44
> zdef 1 levels 1000.0
> tdef 60 linear 12Z16jan2001 1mo
> vars 4
> time=>t 0 t time (kjk)
> rlon=>xlon 0 y,x longitude (degrees_east)
> rlat=>xlat 0 y,x latitude (degrees_north)
> tas=>tas 0 t,y,x Near-Surface Air Temperature (K)
> endvars
> ===================================================
> it doesn’t works.
>
> Following is the information from ncdump -c command:
>
> [☃ 16:04 ~/climate/CORDEX/hist/HadGEM2-ES]>> ncdump -c tas_AFR-44_MOHC-HadGEM2-ES_historical_r1i1p1_SMHI-RCA4_v1_mon_200101-200512.nc
> netcdf tas_AFR-44_MOHC-HadGEM2-ES_historical_r1i1p1_SMHI-RCA4_v1_mon_200101-200512 {
> dimensions:
> time = UNLIMITED ; // (60 currently)
> bnds = 2 ;
> rlon = 194 ;
> rlat = 201 ;
> variables:
> double time(time) ;
> time:axis = "T" ;
> time:bounds = "time_bnds" ;
> time:calendar = "360_day" ;
> time:long_name = "time" ;
> time:standard_name = "time" ;
> time:units = "days since 1949-12-01 00:00:00" ;
> double lon(rlat, rlon) ;
> lon:standard_name = "longitude" ;
> lon:long_name = "longitude" ;
> lon:units = "degrees_east" ;
> double lat(rlat, rlon) ;
> lat:standard_name = "latitude" ;
> lat:long_name = "latitude" ;
> lat:units = "degrees_north" ;
> double time_bnds(time, bnds) ;
> time_bnds:units = "days since 1949-12-01 00:00:00" ;
> time_bnds:calendar = "360_day" ;
> float tas(time, rlat, rlon) ;
> tas:standard_name = "air_temperature" ;
> tas:long_name = "Near-Surface Air Temperature" ;
> tas:units = "K" ;
> tas:coordinates = "lon lat height" ;
> tas:_FillValue = 1.e+20f ;
> tas:cell_methods = "time: mean" ;
> tas:grid_mapping = "rotated_pole" ;
> tas:missing_value = 1.e+20f ;
> double rlon(rlon) ;
> rlon:standard_name = "grid_longitude" ;
> rlon:long_name = "longitude in rotated pole grid" ;
> rlon:units = "degrees" ;
> rlon:axis = "X" ;
> double rlat(rlat) ;
> rlat:standard_name = "grid_latitude" ;
> rlat:long_name = "latitude in rotated pole grid" ;
> rlat:units = "degrees" ;
> rlat:axis = "Y" ;
> char rotated_pole ;
> rotated_pole:grid_mapping_name = "rotated_latitude_longitude" ;
> rotated_pole:grid_north_pole_latitude = 90. ;
> rotated_pole:grid_north_pole_longitude = -180. ;
> double height ;
> height:axis = "Z" ;
> height:long_name = "height" ;
> height:positive = "up" ;
> height:standard_name = "height" ;
> height:units = "m" ;
>
> // global attributes:
> :Conventions = "CF-1.4" ;
> :institution = "Swedish Meteorological and Hydrological Institute, Rossby Centre" ;
> :contact = "rossby.cordex at smhi.se" ;
> :creation_date = "2012-08-03-T15:42:05Z" ;
> :experiment = "historical" ;
> :experiment_id = "historical" ;
> :driving_experiment = "MOHC-HadGEM2-ES, historical, r1i1p1" ;
> :driving_model_id = "MOHC-HadGEM2-ES" ;
> :driving_model_ensemble_member = "r1i1p1" ;
> :driving_experiment_name = "historical" ;
> :frequency = "mon" ;
> :institute_id = "SMHI" ;
> :model_id = "SMHI-RCA4" ;
> :rcm_version_id = "v1" ;
> :project_id = "CORDEX" ;
> :CORDEX_domain = "AFR-44" ;
> :product = "output" ;
> :references = "http://www.smhi.se/en/Research/Research-departments/climate-research-rossby-centre" ;
> :tracking_id = "d2bf2be1-6f30-41af-8d4b-b71a839ab358" ;
> :rossby_comment = "201113: CORDEX Africa 0.44 deg | RCA4 v1 | MOHC-HadGEM2-ES | r1i1p1 | historical | L40" ;
> :rossby_run_id = "201113" ;
> :rossby_grib_path = "/nobackup/rossby15/rossby/joint_exp/cordex/201113/raw/" ;
> data:
>
> time = 18405, 18435, 18465, 18495, 18525, 18555, 18585, 18615, 18645, 18675,
> 18705, 18735, 18765, 18795, 18825, 18855, 18885, 18915, 18945, 18975,
> 19005, 19035, 19065, 19095, 19125, 19155, 19185, 19215, 19245, 19275,
> 19305, 19335, 19365, 19395, 19425, 19455, 19485, 19515, 19545, 19575,
> 19605, 19635, 19665, 19695, 19725, 19755, 19785, 19815, 19845, 19875,
> 19905, 19935, 19965, 19995, 20025, 20055, 20085, 20115, 20145, 20175 ;
>
> rlon = -24.64, -24.2, -23.76, -23.32, -22.88, -22.44, -22, -21.56, -21.12,
> -20.68, -20.24, -19.8, -19.36, -18.92, -18.48, -18.04, -17.6, -17.16,
> -16.72, -16.28, -15.84, -15.4, -14.96, -14.52, -14.08, -13.64, -13.2,
> -12.76, -12.32, -11.88, -11.44, -11, -10.56, -10.12, -9.68, -9.24, -8.8,
> -8.36, -7.92, -7.48, -7.04, -6.6, -6.16, -5.72, -5.28, -4.84, -4.4,
> -3.96, -3.52, -3.08, -2.64, -2.2, -1.76, -1.32, -0.879999999999999,
> -0.440000000000001, 0, 0.440000000000001, 0.879999999999999, 1.32, 1.76,
> 2.2, 2.64, 3.08, 3.52, 3.96, 4.4, 4.84, 5.28, 5.72, 6.16, 6.6, 7.04,
> 7.48, 7.92, 8.36, 8.8, 9.24, 9.68, 10.12, 10.56, 11, 11.44, 11.88, 12.32,
> 12.76, 13.2, 13.64, 14.08, 14.52, 14.96, 15.4, 15.84, 16.28, 16.72,
> 17.16, 17.6, 18.04, 18.48, 18.92, 19.36, 19.8, 20.24, 20.68, 21.12,
> 21.56, 22, 22.44, 22.88, 23.32, 23.76, 24.2, 24.64, 25.08, 25.52, 25.96,
> 26.4, 26.84, 27.28, 27.72, 28.16, 28.6, 29.04, 29.48, 29.92, 30.36, 30.8,
> 31.24, 31.68, 32.12, 32.56, 33, 33.44, 33.88, 34.32, 34.76, 35.2, 35.64,
> 36.08, 36.52, 36.96, 37.4, 37.84, 38.28, 38.72, 39.16, 39.6, 40.04,
> 40.48, 40.92, 41.36, 41.8, 42.24, 42.68, 43.12, 43.56, 44, 44.44, 44.88,
> 45.32, 45.76, 46.2, 46.64, 47.08, 47.52, 47.96, 48.4, 48.84, 49.28,
> 49.72, 50.16, 50.6, 51.04, 51.48, 51.92, 52.36, 52.8, 53.24, 53.68,
> 54.12, 54.56, 55, 55.44, 55.88, 56.32, 56.76, 57.2, 57.64, 58.08, 58.52,
> 58.96, 59.4, 59.84, 60.28 ;
>
> rlat = -45.76, -45.32, -44.88, -44.44, -44, -43.56, -43.12, -42.68, -42.24,
> -41.8, -41.36, -40.92, -40.48, -40.04, -39.6, -39.16, -38.72, -38.28,
> -37.84, -37.4, -36.96, -36.52, -36.08, -35.64, -35.2, -34.76, -34.32,
> -33.88, -33.44, -33, -32.56, -32.12, -31.68, -31.24, -30.8, -30.36,
> -29.92, -29.48, -29.04, -28.6, -28.16, -27.72, -27.28, -26.84, -26.4,
> -25.96, -25.52, -25.08, -24.64, -24.2, -23.76, -23.32, -22.88, -22.44,
> -22, -21.56, -21.12, -20.68, -20.24, -19.8, -19.36, -18.92, -18.48,
> -18.04, -17.6, -17.16, -16.72, -16.28, -15.84, -15.4, -14.96, -14.52,
> -14.08, -13.64, -13.2, -12.76, -12.32, -11.88, -11.44, -11, -10.56,
> -10.12, -9.68, -9.23999999999999, -8.8, -8.36, -7.91999999999999, -7.48,
> -7.04, -6.59999999999999, -6.16, -5.72, -5.28, -4.84, -4.4, -3.96, -3.52,
> -3.08, -2.64, -2.2, -1.76, -1.32, -0.879999999999995, -0.439999999999998,
> 0, 0.440000000000005, 0.880000000000003, 1.32, 1.76000000000001, 2.2,
> 2.64, 3.08000000000001, 3.52, 3.96, 4.40000000000001, 4.84, 5.28, 5.72,
> 6.16, 6.6, 7.04, 7.48, 7.92, 8.36, 8.8, 9.24, 9.68, 10.12, 10.56, 11,
> 11.44, 11.88, 12.32, 12.76, 13.2, 13.64, 14.08, 14.52, 14.96, 15.4,
> 15.84, 16.28, 16.72, 17.16, 17.6, 18.04, 18.48, 18.92, 19.36, 19.8,
> 20.24, 20.68, 21.12, 21.56, 22, 22.44, 22.88, 23.32, 23.76, 24.2, 24.64,
> 25.08, 25.52, 25.96, 26.4, 26.84, 27.28, 27.72, 28.16, 28.6, 29.04,
> 29.48, 29.92, 30.36, 30.8, 31.24, 31.68, 32.12, 32.56, 33, 33.44, 33.88,
> 34.32, 34.76, 35.2, 35.64, 36.08, 36.52, 36.96, 37.4, 37.84, 38.28,
> 38.72, 39.16, 39.6, 40.04, 40.48, 40.92, 41.36, 41.8, 42.24 ;
> }
>
>
> ===================================================
>
> Could you please help me to correct the descriptor file?
> And is there any other method to create the descriptor file?
> Since these data release is follow the CF-1.4 (or later) conventions, they should be easily read by GrADS, right?
>
>
> Thanks for your attention.
>
>
> Best regards,
> Chao TANG
> -------------------------------------------------------------------------------------------------
> Laboratoire d'Energétique, d'Electronique et Procédés
> Unité de Recherche EA 4079
> Université de La Réunion, LE2P
> 15 avenue René Cassin CS 92003
> 97744 ST DENIS CEDEX 9
> Mobile: 0693 91 57 38
> Courriel: chao.tang at univ-reunion.fr
> -------------------------------------------------------------------------------------------------
>
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--
Jennifer M. Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
111 Research Hall, Mail Stop 2B3
George Mason University
4400 University Drive
Fairfax, VA 22030
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