CF data model

The CF (Climate and Forecast) metadata conventions (http://cfconventions.org) provide a description of the physical meaning of data and of their spatial and temporal properties and are designed to promote the creation, processing, and sharing of climate and forecasting data using netCDF files and libraries (https://www.unidata.ucar.edu/software/netcdf).

The CF data model [1] identifies the fundamental elements (“constructs”) of the CF conventions and shows how they relate to each other, independently of the netCDF encoding.

The field construct defined by the CF data model, which corresponds to a CF-netCDF data variable with all of its metadata, is the central construct that includes all of the other constructs. It consists of

  • descriptive properties that apply to field construct as a whole (e.g. the standard name),
  • a data array, and
  • “metadata constructs” that describe
    • the locations of each cell of the data array (i.e. the “domain”), and
    • the physical nature of each cell’s datum.

The domain is defined by

  • domain axis constructs (corresponding to CF-netCDF dimensions or scalar coordinate variables),
  • dimension coordinate constructs (corresponding to CF-netCDF coordinate variables or numeric scalar coordinate variables),
  • auxiliary coordinate constructs (corresponding to CF-netCDF auxiliary coordinate variables and non-numeric scalar coordinate variables),
  • coordinate reference constructs (corresponding to CF-netCDF grid mapping variables or the formula_terms attribute of a coordinate variable),
  • domain ancillary constructs (corresponding to CF-netCDF variables named by the formula_terms attribute of a coordinate variable), and
  • cell measure constructs (corresponding to CF-netCDF cell measure variables).

The physical nature of individual data values are described by

  • field ancillary constructs (corresponding to CF-netCDF ancillary variables), and
  • cell method constructs (corresponding to a CF-netCDF cell_methods attribute of data variable).
[1]Hassell, D., Gregory, J., Blower, J., Lawrence, B. N., and Taylor, K. E.: A data model of the Climate and Forecast metadata conventions (CF-1.6) with a software implementation (cf-python v2.1), Geosci. Model Dev., 10, 4619-4646, https://doi.org/10.5194/gmd-10-4619-2017, 2017.