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Re: Does TDS really synthesize CF curvilinear coordinates for GRIB data?



are you asking this to be done on motherlode, or one of your servers?

we deliberately dont use 2D coordinates because of their size, and because the calculation can be done on the (our) client, which is more efficient.

what is your use case?



Steve Hankin wrote:
Hi John,

Yes -- this is the Motherlode TDS.

Looking at the first link as an example, it contains a variable, "Polar_Stereographic", whose attributes describe the projection. There are "grid_mapping" attributes that point to it for the relevant dependent variables. So much of the CF compliance work has been done. What remains is for the IOSP to

   1. note that the grid_mapping machinery exists for a particular file
   2. inspect the grid_mapping parameters
   3. synthesize the latitude and longitude coordinate variables
   4. fix up the "coordinates" attributes of the dependent variables so
      that instead of pointing to

        coordinates: "run time y x"

           they point to

        coordinates: "run time    *my_synth_latitude    my_synth_longitude*"

    - Steve

=================

John Caron wrote:
Steve Hankin wrote:
Hi John,

At the NCDC meeting we talked about IOPS's for various binary data formats. I *thought* I heard you say that the recent TDS IOSP for GRIB data would automatically synthesize the CF curvilinear coordinates. When I look at examples like the ones below on Motherlode, I spot only coordinates in kilometers. (polar stereographic and lambert conformal examples listed below)

Did I misunderstand something? What is your recommendation for getting generating the curvilinear (CF) coordinate variables that we need for the UAF project? We don't want to do it manually if it is already a solved problem.

   sorry to trouble you.  I know you're busy - Steve

http://motherlode.ucar.edu:8080/thredds/dodsC/fmrc/NCEP/GFS/Alaska_191km/NCEP-GFS-Alaska_191km_fmrc.ncd.html

http://motherlode.ucar.edu:8080/thredds/dodsC/fmrc/NCEP/RUC2/CONUS_20km/surface/NCEP-RUC2-CONUS_20km-surface_best.ncd.html


we dont automatically generate the 2D coords, but we could. the main issue would be to figure out how to tell the GRIB IOSP to do so, ie configuration. Would this be a global setting, or per-dataset? I assume this is coming through a TDS?


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