Karl,
how do you deal with the type axis in a practical manner? How does
one select a particular 'type' axis value for plotting ?
I see there is no "type" coordinate variable, so the
landCoverFrac:coordinates = "type_description" attribute is used for
treating that dimension.
Regards,
Etienne
On Mon, Jun 4, 2012 at 3:08 PM, Karl Taylor <taylor13 at llnl.gov> wrote:
> Dear Etienne, Jonathan, and all,
>
> For CMIP5, I've ncdumped below some of the information in the Plant
> Functional Type Grid Fraction".? We asked the groups to include a precise
> description of the plant function type in a variable named
> "type_description", but this is not standardized.? Note that the coordinate
> "type" is a simple index and again is not standardized across models.
>
> regards,
> Karl
> ncdump landCoverFrac_Lmon_MPI-ESM-LR_1pctCO2_r1i1p1_199001-199912.nc | more
> netcdf landCoverFrac_Lmon_MPI-ESM-LR_1pctCO2_r1i1p1_199001-199912 {
> dimensions:
> ??????? time = UNLIMITED ; // (120 currently)
> ??????? type = 13 ;
> ??????? lat = 96 ;
> ??????? lon = 192 ;
> ??????? bnds = 2 ;
> ??????? strlen = 34 ;
> variables:
> ??????? double time(time) ;
> ??????????????? time:bounds = "time_bnds" ;
> ??????????????? time:units = "days since 1850-1-1 00:00:00" ;
> ??????????????? time:calendar = "proleptic_gregorian" ;
> ??????????????? time:axis = "T" ;
> ??????????????? time:long_name = "time" ;
> ??????????????? time:standard_name = "time" ;
> ??????? double time_bnds(time, bnds) ;
> ??????? char type_description(type, strlen) ;
> ??????????????? type_description:long_name = "plant functional type" ;
> ??????????????? type_description:standard_name = "area_type" ;
> ??????? double lat(lat) ;
> ??????????????? lat:bounds = "lat_bnds" ;
> ??????????????? lat:units = "degrees_north" ;
> ??????????????? lat:axis = "Y" ;
> ??????????????? lat:long_name = "latitude" ;
> ??????????????? lat:standard_name = "latitude" ;
> ??????? double lat_bnds(lat, bnds) ;
> ??????? double lon(lon) ;
> ??????????????? lon:bounds = "lon_bnds" ;
> ??????????????? lon:units = "degrees_east" ;
> ??????????????? lon:axis = "X" ;
> ??????????????? lon:long_name = "longitude" ;
> ??????????????? lon:standard_name = "longitude" ;
> ??????? double lon_bnds(lon, bnds) ;
> ??????? float landCoverFrac(time, type, lat, lon) ;
> ??????????????? landCoverFrac:standard_name = "area_fraction" ;
> ??????????????? landCoverFrac:long_name = "Plant Functional Type Grid
> Fraction" ;
> ??????????????? landCoverFrac:comment = "The categories may differ from
> model to model, depending on their? PFT definitions.?? This may include
> natural PFTs, anthropogenic PFTs, bare soil, lakes, urban areas, etc.?? Sum
> of all should equal the fraction of the grid-cell
> that is land." ;
> ??????????????? landCoverFrac:units = "%" ;
> ??????????????? landCoverFrac:cell_methods = "time: mean" ;
> ??????????????? landCoverFrac:cell_measures = "area: areacella" ;
> ??????????????? landCoverFrac:history = "2011-06-01T05:07:12Z altered by
> CMOR: replaced missing value flag (1e+22) with standard missing value
> (1e+20)." ;
> ??????????????? landCoverFrac:missing_value = 1.e+20f ;
> ??????????????? landCoverFrac:_FillValue = 1.e+20f ;
> ??????????????? landCoverFrac:associated_files = "baseURL:
> http://cmip-pcmdi.llnl.gov/CMIP5/dataLocation gridspecFile:
> gridspec_land_fx_MPI-ESM-LR_1pctCO2_r0i0p0.nc areacella:
> areacella_fx_MPI-ESM-LR_1pctCO2_r0i0p0.nc" ;
> ??????????????? landCoverFrac:coordinates = "type_description" ;
>
> // global attributes:
> ??????????????? :institution = "Max Planck Institute for Meteorology" ;
> ??????????????? :institute_id = "MPI-M" ;
> ??????????????? :experiment_id = "1pctCO2" ;
> ??????????????? :source = "MPI-ESM-LR 2011; URL:
> http://svn.zmaw.de/svn/cosmos/branches/releases/mpi-esm-cmip5/src/mod;
> atmosphere: ECHAM6 (REV: 4571), T63L47; land: JSBACH (REV: 4571); ocean:
> MPIOM (REV: 4571), GR15L40; sea ice: 4571; marine bgc: HAMOCC (REV: 4571);"
>
> ??????????????? :model_id = "MPI-ESM-LR" ;
> ??????????????? :forcing = "N/A" ;
> ??????????????? :parent_experiment_id = "piControl" ;
> ??????????????? :parent_experiment_rip = "r1i1p1" ;
> ??????????????? :branch_time = 10957. ;
> ??????????????? :contact = "cmip5-mpi-esm at dkrz.de" ;
> ??????????????? :history = "Model raw output postprocessing with modelling
> environment (IMDI) at DKRZ: URL:
> http://svn-mad.zmaw.de/svn/mad/Model/IMDI/trunk, REV: 3208
> 2011-06-01T05:07:12Z CMOR rewrote data to comply with CF standards and CMIP5
> requirements." ;
> ??????????????? :references = "ECHAM6: n/a; JSBACH: Raddatz et al., 2007.
> Will the tropical land biosphere dominate the climate-carbon cycle feedback
> during the twenty first century? Climate Dynamics, 29, 565-574, doi
> 10.1007/s00382-007-0247-8;? MPIOM: Marsland et al.,
> 2003. The Max-Planck-Institute global ocean/sea ice model with orthogonal
> curvilinear coordinates. Ocean Modelling, 5, 91-127;? HAMOCC:
> http://www.mpimet.mpg.de/fileadmin/models/MPIOM/HAMOCC5.1_TECHNICAL_REPORT.pdf;"
> ;
> ??????????????? :initialization_method = 1 ;
> ??????????????? :physics_version = 1 ;
> ??????????????? :tracking_id = "91871851-f604-400d-a473-10ebc3a98638" ;
> ??????????????? :product = "output" ;
> ??????????????? :experiment = "1 percent per year CO2" ;
> ??????????????? :frequency = "mon" ;
> ??????????????? :creation_date = "2011-06-01T05:07:12Z" ;
> ??????????????? :Conventions = "CF-1.4" ;
> ??????????????? :project_id = "CMIP5" ;
> ??????????????? :table_id = "Table Lmon (27 April 2011)
> c4244dce0826a43bb0b259f293e2f742" ;
> ??????????????? :title = "MPI-ESM-LR model output prepared for CMIP5 1
> percent per year CO2" ;
> ??????????????? :parent_experiment = "pre-industrial control" ;
> ??????????????? :modeling_realm = "land" ;
> ??????????????? :realization = 1 ;
> ??????????????? :cmor_version = "2.5.9" ;
> data:
>
> .
> .
> .
> .
>
>
> ?type_description =
> ? "glacier?????????????????????????? ",
> ? "tropical broadleaf evergreen trees",
> ? "tropical broadleaf deciduous trees",
> ? "extra-tropical evergreen trees??? ",
> ? "extra-tropical deciduous trees??? ",
> ? "raingreen shrubs????????????????? ",
> ? "deciduous shrubs????????????????? ",
> ? "C3grass?????????????????????????? ",
> ? "C4grass?????????????????????????? ",
> ? "C3 pasture??????????????????????? ",
> ? "C4 pasture??????????????????????? ",
> ? "C3crops?????????????????????????? ",
> ? "C4crops?????????????????????????? " ;
>
> .
> .
> .
> .
>
>
>
>
>
>
>
> On 6/4/12 10:17 AM, Jonathan Gregory wrote:
>
> Dear Etienne
>
> I think the structure you have adopted for the data is fine.
>
> double pft(pft) ;
> pft:long_name = "plant functional type" ;
> pft:units = "none" ;
>
> double npp(time, pft, latitude, longitude) ;
> npp:long_name = "npp of carbon for each pft" ;
> npp:units = "kg m-2 year-1" ;
>
> The specific problem you raise is concerned with the axis attribute. That
> attribute is really intended for identifying spatiotemporal coordinates;
> although it may be convenient, it is redundant because they can also be
> identified in other ways. It has not been extended for non-spatiotemporal
> axes like pft. In your CDL, the pft axis is identified by its long_name.
> To make this more reliable, you might want to use a standard_name for this
> pft coordinate variable. There isn't such a standard_name at present, but
> area_type is often vegetation type in practice, so you could perhaps use
> that. We could standardise new area_types by proposals to this email list.
>
> Also, there is the new proposal, which I expect will go into the
> standard_name table, for UN/FAO land cover types, which in many cases are
> also vegetation types.
> See http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2012/033507.html
>
> The quantities identified by these standard_names are string-valued, whereas
> you expect a numeric pft. However, a string-valued one could be encoded as a
> number by using the flag_values and flag_meanings attributes.
>
> There is an existing standard name for NPP as well viz
> net_primary_productivity_of_carbon (kg m-2 s-1)
>
> Best wishes
>
> Jonathan
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Received on Mon Jun 04 2012 - 13:24:22 BST
