Custom Query (124 matches)

The various vertical coordinates described by Appendix D of the CF standard should be titled as unnumbered subsections, not as examples. They were unnumbered subsections in the beta CF standard document, and the formatting was changed when the document was translated to docbook. There was a similar problem with Appendix F, which was corrected by ticket 18.

Jonathan

1. Title

Conventions for Point Observation Data

2. Moderator

Steve Hankin

3. Requirement

Current conventions are oriented towards gridded data. This proposal extends the framework to specify how to encode "point observation" data.

4. Initial Statement of Technical Proposal

We show six types of point observational data, and describe a general way to encode many variations. The main technical extension is a simple way to describe ragged arrays, for the case when rectangular arrays are too inefficient.

5. Benefits

• Many data providers would like to use CF conventions when storing their observational data.

• This will allow a standard for converting things like BUFR data into netCDF.

6. Status Quo

Currently sections 5.4 and 5.5 describe 2 examples of point observations (station time series and trajectories). This proposal generalizes those.

7. Detailed Proposal

Because of the length of this, I have written it as a ​Microsoft Word file to make it easy to edit. I can reformat later when it is close to being finished.

Some background docs and earlier drafts:

• ​CDM Feature Types

• ​CDM Point Feature Types

• ​Draft 2 of proposed spec for Point Observation netCDF encoding

• ​Another draft of the proposed spec, last revision was October 2010

3.1 of the convention states that "The units attribute is required for all variables that represent dimensional quantities."

Yet a Netcdf file like the following does not generate errors indicating that the units attribute is missing for any of the coordinate variables.

dimensions:
       longitude = 144 ;
       latitude = 91 ;
       press = 10 ;
       species = 6 ;
       rec = UNLIMITED ; // (12 currently)
       word = 13 ;

variables:
       float concentrations(rec, species, press, latitude, longitude) ;
             concentrations:long_name = "CFC concentrations" ;
             concentrations:Units = "pptv" ;
       float longitude(longitude) ;
       float latitude(latitude) ;
       float press(press) ;
       float species(species) ;
             species:long_name = "species" ;
             species:coord_labels = "species" ;
             species:selection_category = "NULL" ;
       float rec(rec) ;
             rec:long_name = "month" ;
             rec:coord_labels = "month" ;
             rec:selection_category = "NULL" ;
       char const_labels(species, word) ;
             const_labels:selection_category = "NULL" ;
       char month(rec, word) ;
             month:selection_category = "NULL" ;
}