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

The CF data model defines a field construct for storing data with all of its metadata. It is defined as follows:

field construct

corresponds to a CF-netCDF data variable with all of its metadata. It consists of

  • descriptive properties that apply to field construct as a whole (e.g. the standard name),

  • a data array,

  • a domain construct that describes the locations of each cell of the data array (i.e. the “domain”),

  • metadata constructs that describe the physical nature of the data array, defined by

    field ancillary constructs

    corresponding to CF-netCDF ancillary variables

    cell method constructs

    corresponding to a CF-netCDF cell_methods attribute of data variable

domain construct

that describes the locations of each cell of the domain. It may exist independently of a field construct and consists of

  • descriptive properties that apply to domain construct as a whole,

  • metadata constructs that describe the locations of each cell of the domain, 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

cell measure constructs

corresponding to CF-netCDF cell measure variables


_images/cfdm_field.svg

The constructs of the CF data model described using UML. The field construct corresponds to a CF-netCDF data variable. The domain construct provides the linkage between the field construct and the constructs which describe measurement locations and cell properties. It is useful to define an abstract generic coordinate construct that can be used to refer to coordinates when the their type (dimension or auxiliary coordinate construct) is not an issue.